Source code for sympy.polys.polytools

"""User-friendly public interface to polynomial functions. """

from sympy.core import (
    S, Basic, Expr, I, Integer, Add, Mul, Dummy, Tuple, Rational
)

from sympy.core.mul import _keep_coeff

from sympy.core.sympify import (
    sympify, SympifyError,
)

from sympy.core.decorators import (
    _sympifyit,
)

from sympy.polys.polyclasses import DMP

from sympy.polys.polyutils import (
    basic_from_dict,
    _sort_gens,
    _unify_gens,
    _dict_reorder,
    _dict_from_expr,
    _parallel_dict_from_expr,
)

from sympy.polys.rationaltools import (
    together,
)

from sympy.polys.rootisolation import (
    dup_isolate_real_roots_list,
)

from sympy.polys.distributedpolys import (
    sdp_from_dict, sdp_div,
)

from sympy.polys.groebnertools import (
    sdp_groebner, matrix_fglm,
)

from sympy.polys.monomialtools import (
    Monomial, monomial_key,
)

from sympy.polys.polyerrors import (
    OperationNotSupported, DomainError,
    CoercionFailed, UnificationFailed,
    GeneratorsNeeded, PolynomialError,
    MultivariatePolynomialError,
    ExactQuotientFailed,
    PolificationFailed,
    ComputationFailed,
    GeneratorsError,
)

from sympy.utilities import group

import sympy.polys
import sympy.mpmath

from sympy.polys.domains import FF, QQ
from sympy.polys.constructor import construct_domain

from sympy.polys import polyoptions as options

from sympy.core.compatibility import iterable

[docs]class Poly(Expr): """Generic class for representing polynomial expressions. """ __slots__ = ['rep', 'gens'] is_Poly = True def __new__(cls, rep, *gens, **args): """Create a new polynomial instance out of something useful. """ opt = options.build_options(gens, args) if 'order' in opt: raise NotImplementedError("'order' keyword is not implemented yet") if iterable(rep, exclude=str): if isinstance(rep, dict): return cls._from_dict(rep, opt) else: return cls._from_list(list(rep), opt) else: rep = sympify(rep) if rep.is_Poly: return cls._from_poly(rep, opt) else: return cls._from_expr(rep, opt) @classmethod
[docs] def new(cls, rep, *gens): """Construct :class:`Poly` instance from raw representation. """ if not isinstance(rep, DMP): raise PolynomialError("invalid polynomial representation: %s" % rep) elif rep.lev != len(gens)-1: raise PolynomialError("invalid arguments: %s, %s" % (rep, gens)) obj = Basic.__new__(cls) obj.rep = rep obj.gens = gens return obj
@classmethod
[docs] def from_dict(cls, rep, *gens, **args): """Construct a polynomial from a ``dict``. """ opt = options.build_options(gens, args) return cls._from_dict(rep, opt)
@classmethod
[docs] def from_list(cls, rep, *gens, **args): """Construct a polynomial from a ``list``. """ opt = options.build_options(gens, args) return cls._from_list(rep, opt)
@classmethod
[docs] def from_poly(cls, rep, *gens, **args): """Construct a polynomial from a polynomial. """ opt = options.build_options(gens, args) return cls._from_poly(rep, opt)
@classmethod
[docs] def from_expr(cls, rep, *gens, **args): """Construct a polynomial from an expression. """ opt = options.build_options(gens, args) return cls._from_expr(rep, opt)
@classmethod def _from_dict(cls, rep, opt): """Construct a polynomial from a ``dict``. """ gens = opt.gens if not gens: raise GeneratorsNeeded("can't initialize from 'dict' without generators") level = len(gens)-1 domain = opt.domain if domain is None: domain, rep = construct_domain(rep, opt=opt) else: for monom, coeff in rep.items(): rep[monom] = domain.convert(coeff) return cls.new(DMP.from_dict(rep, level, domain), *gens) @classmethod def _from_list(cls, rep, opt): """Construct a polynomial from a ``list``. """ gens = opt.gens if not gens: raise GeneratorsNeeded("can't initialize from 'list' without generators") elif len(gens) != 1: raise MultivariatePolynomialError("'list' representation not supported") level = len(gens)-1 domain = opt.domain if domain is None: domain, rep = construct_domain(rep, opt=opt) else: rep = list(map(domain.convert, rep)) return cls.new(DMP.from_list(rep, level, domain), *gens) @classmethod def _from_poly(cls, rep, opt): """Construct a polynomial from a polynomial. """ if cls != rep.__class__: rep = cls.new(rep.rep, *rep.gens) gens = opt.gens field = opt.field domain = opt.domain if gens and rep.gens != gens: if set(rep.gens) != set(gens): return cls._from_expr(rep.as_expr(), opt) else: rep = rep.reorder(*gens) if 'domain' in opt and domain: rep = rep.set_domain(domain) elif field is True: rep = rep.to_field() return rep @classmethod def _from_expr(cls, rep, opt): """Construct a polynomial from an expression. """ rep, opt = _dict_from_expr(rep, opt) return cls._from_dict(rep, opt) def _hashable_content(self): """Allow SymPy to hash Poly instances. """ return (self.rep, self.gens) def __hash__(self): return super(Poly, self).__hash__() @property
[docs] def free_symbols(self): """ Free symbols of a polynomial expression. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x, y >>> Poly(x**2 + 1).free_symbols set([x]) >>> Poly(x**2 + y).free_symbols set([x, y]) >>> Poly(x**2 + y, x).free_symbols set([x, y]) """ symbols = set([]) for gen in self.gens: symbols |= gen.free_symbols return symbols | self.free_symbols_in_domain
@property
[docs] def free_symbols_in_domain(self): """ Free symbols of the domain of ``self``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x, y >>> Poly(x**2 + 1).free_symbols_in_domain set() >>> Poly(x**2 + y).free_symbols_in_domain set() >>> Poly(x**2 + y, x).free_symbols_in_domain set([y]) """ domain, symbols = self.rep.dom, set() if domain.is_Composite: for gen in domain.gens: symbols |= gen.free_symbols elif domain.is_EX: for coeff in self.coeffs(): symbols |= coeff.free_symbols return symbols
@property
[docs] def args(self): """ Don't mess up with the core. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(x**2 + 1, x).args (x**2 + 1,) """ return (self.as_expr(),)
@property
[docs] def gen(self): """ Return the principal generator. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(x**2 + 1, x).gen x """ return self.gens[0]
@property
[docs] def domain(self): """Get the ground domain of ``self``. """ return self.get_domain()
@property
[docs] def zero(self): """Return zero polynomial with ``self``'s properties. """ return self.new(self.rep.zero(self.rep.lev, self.rep.dom), *self.gens)
@property
[docs] def one(self): """Return one polynomial with ``self``'s properties. """ return self.new(self.rep.one(self.rep.lev, self.rep.dom), *self.gens)
@property
[docs] def unit(self): """Return unit polynomial with ``self``'s properties. """ return self.new(self.rep.unit(self.rep.lev, self.rep.dom), *self.gens)
[docs] def unify(f, g): """ Make ``f`` and ``g`` belong to the same domain. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x, y >>> f, g = Poly(x/2 + 1), Poly(2*x + 1) >>> f Poly(1/2*x + 1, x, domain='QQ') >>> g Poly(2*x + 1, x, domain='ZZ') >>> F, G = f.unify(g) >>> F Poly(1/2*x + 1, x, domain='QQ') >>> G Poly(2*x + 1, x, domain='QQ') """ _, per, F, G = f._unify(g) return per(F), per(G)
def _unify(f, g): g = sympify(g) if not g.is_Poly: try: return f.rep.dom, f.per, f.rep, f.rep.per(f.rep.dom.from_sympy(g)) except CoercionFailed: raise UnificationFailed("can't unify %s with %s" % (f, g)) if isinstance(f.rep, DMP) and isinstance(g.rep, DMP): gens = _unify_gens(f.gens, g.gens) dom, lev = f.rep.dom.unify(g.rep.dom, gens), len(gens)-1 if f.gens != gens: f_monoms, f_coeffs = _dict_reorder(f.rep.to_dict(), f.gens, gens) if f.rep.dom != dom: f_coeffs = [ dom.convert(c, f.rep.dom) for c in f_coeffs ] F = DMP(dict(list(zip(f_monoms, f_coeffs))), dom, lev) else: F = f.rep.convert(dom) if g.gens != gens: g_monoms, g_coeffs = _dict_reorder(g.rep.to_dict(), g.gens, gens) if g.rep.dom != dom: g_coeffs = [ dom.convert(c, g.rep.dom) for c in g_coeffs ] G = DMP(dict(list(zip(g_monoms, g_coeffs))), dom, lev) else: G = g.rep.convert(dom) else: raise UnificationFailed("can't unify %s with %s" % (f, g)) cls = f.__class__ def per(rep, dom=dom, gens=gens, remove=None): if remove is not None: gens = gens[:remove]+gens[remove+1:] if not gens: return dom.to_sympy(rep) return cls.new(rep, *gens) return dom, per, F, G
[docs] def per(f, rep, gens=None, remove=None): """ Create a Poly out of the given representation. Examples ======== >>> from sympy import Poly, ZZ >>> from sympy.abc import x, y >>> from sympy.polys.polyclasses import DMP >>> a = Poly(x**2 + 1) >>> a.per(DMP([ZZ(1), ZZ(1)], ZZ), gens=[y]) Poly(y + 1, y, domain='ZZ') """ if gens is None: gens = f.gens if remove is not None: gens = gens[:remove]+gens[remove+1:] if not gens: return f.rep.dom.to_sympy(rep) return f.__class__.new(rep, *gens)
[docs] def set_domain(f, domain): """Set the ground domain of ``f``. """ opt = options.build_options(f.gens, {'domain': domain}) return f.per(f.rep.convert(opt.domain))
[docs] def get_domain(f): """Get the ground domain of ``f``. """ return f.rep.dom
[docs] def set_modulus(f, modulus): """ Set the modulus of ``f``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(5*x**2 + 2*x - 1, x).set_modulus(2) Poly(x**2 + 1, x, modulus=2) """ modulus = options.Modulus.preprocess(modulus) return f.set_domain(FF(modulus))
[docs] def get_modulus(f): """ Get the modulus of ``f``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(x**2 + 1, modulus=2).get_modulus() 2 """ domain = f.get_domain() if not domain.has_CharacteristicZero: return Integer(domain.characteristic()) else: raise PolynomialError("not a polynomial over a Galois field")
def _eval_subs(f, old, new): """Internal implementation of :func:`subs`. """ if old in f.gens: if new.is_number: return f.eval(old, new) else: try: return f.replace(old, new) except PolynomialError: pass return f.as_expr().subs(old, new)
[docs] def exclude(f): """ Remove unnecessary generators from ``f``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import a, b, c, d, x >>> Poly(a + x, a, b, c, d, x).exclude() Poly(a + x, a, x, domain='ZZ') """ J, new = f.rep.exclude() gens = [] for j in range(len(f.gens)): if j not in J: gens.append(f.gens[j]) return f.per(new, gens=gens)
[docs] def replace(f, x, y=None): """ Replace ``x`` with ``y`` in generators list. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x, y >>> Poly(x**2 + 1, x).replace(x, y) Poly(y**2 + 1, y, domain='ZZ') """ if y is None: if f.is_univariate: x, y = f.gen, x else: raise PolynomialError("syntax supported only in univariate case") if x == y: return f if x in f.gens and y not in f.gens: dom = f.get_domain() if not dom.is_Composite or y not in dom.gens: gens = list(f.gens) gens[gens.index(x)] = y return f.per(f.rep, gens=gens) raise PolynomialError("can't replace %s with %s in %s" % (x, y, f))
[docs] def reorder(f, *gens, **args): """ Efficiently apply new order of generators. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x, y >>> Poly(x**2 + x*y**2, x, y).reorder(y, x) Poly(y**2*x + x**2, y, x, domain='ZZ') """ opt = options.Options((), args) if not gens: gens = _sort_gens(f.gens, opt=opt) elif set(f.gens) != set(gens): raise PolynomialError("generators list can differ only up to order of elements") rep = dict(list(zip(*_dict_reorder(f.rep.to_dict(), f.gens, gens)))) return f.per(DMP(rep, f.rep.dom, len(gens)-1), gens=gens)
[docs] def ltrim(f, gen): """ Remove dummy generators from the "left" of ``f``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x, y, z >>> Poly(y**2 + y*z**2, x, y, z).ltrim(y) Poly(y**2 + y*z**2, y, z, domain='ZZ') """ rep = f.as_dict(native=True) j = f._gen_to_level(gen) terms = {} for monom, coeff in rep.items(): monom = monom[j:] if monom not in terms: terms[monom] = coeff else: raise PolynomialError("can't left trim %s" % f) gens = f.gens[j:] return f.new(DMP.from_dict(terms, len(gens)-1, f.rep.dom), *gens)
[docs] def has_only_gens(f, *gens): """ Return ``True`` if ``Poly(f, *gens)`` retains ground domain. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x, y, z >>> Poly(x*y + 1, x, y, z).has_only_gens(x, y) True >>> Poly(x*y + z, x, y, z).has_only_gens(x, y) False """ f_gens = list(f.gens) indices = set([]) for gen in gens: try: index = f_gens.index(gen) except ValueError: raise GeneratorsError("%s doesn't have %s as generator" % (f, gen)) else: indices.add(index) for monom in f.monoms(): for i, elt in enumerate(monom): if i not in indices and elt: return False return True
[docs] def to_ring(f): """ Make the ground domain a ring. Examples ======== >>> from sympy import Poly, QQ >>> from sympy.abc import x >>> Poly(x**2 + 1, domain=QQ).to_ring() Poly(x**2 + 1, x, domain='ZZ') """ if hasattr(f.rep, 'to_ring'): result = f.rep.to_ring() else: # pragma: no cover raise OperationNotSupported(f, 'to_ring') return f.per(result)
[docs] def to_field(f): """ Make the ground domain a field. Examples ======== >>> from sympy import Poly, ZZ >>> from sympy.abc import x >>> Poly(x**2 + 1, x, domain=ZZ).to_field() Poly(x**2 + 1, x, domain='QQ') """ if hasattr(f.rep, 'to_field'): result = f.rep.to_field() else: # pragma: no cover raise OperationNotSupported(f, 'to_field') return f.per(result)
[docs] def to_exact(f): """ Make the ground domain exact. Examples ======== >>> from sympy import Poly, RR >>> from sympy.abc import x >>> Poly(x**2 + 1.0, x, domain=RR).to_exact() Poly(x**2 + 1, x, domain='QQ') """ if hasattr(f.rep, 'to_exact'): result = f.rep.to_exact() else: # pragma: no cover raise OperationNotSupported(f, 'to_exact') return f.per(result)
[docs] def retract(f, field=None): """ Recalculate the ground domain of a polynomial. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x, y >>> f = Poly(x**2 + 1, x, domain='QQ[y]') >>> f Poly(x**2 + 1, x, domain='QQ[y]') >>> f.retract() Poly(x**2 + 1, x, domain='ZZ') >>> f.retract(field=True) Poly(x**2 + 1, x, domain='QQ') """ dom, rep = construct_domain(f.as_dict(zero=True), field=field) return f.from_dict(rep, f.gens, domain=dom)
[docs] def slice(f, x, m, n=None): """Take a continuous subsequence of terms of ``f``. """ if n is None: j, m, n = 0, x, m else: j = f._gen_to_level(x) m, n = int(m), int(n) if hasattr(f.rep, 'slice'): result = f.rep.slice(m, n, j) else: # pragma: no cover raise OperationNotSupported(f, 'slice') return f.per(result)
[docs] def coeffs(f, order=None): """ Returns all non-zero coefficients from ``f`` in lex order. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(x**3 + 2*x + 3, x).coeffs() [1, 2, 3] """ return [ f.rep.dom.to_sympy(c) for c in f.rep.coeffs(order=order) ]
[docs] def monoms(f, order=None): """ Returns all non-zero monomials from ``f`` in lex order. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x, y >>> Poly(x**2 + 2*x*y**2 + x*y + 3*y, x, y).monoms() [(2, 0), (1, 2), (1, 1), (0, 1)] """ return f.rep.monoms(order=order)
[docs] def terms(f, order=None): """ Returns all non-zero terms from ``f`` in lex order. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x, y >>> Poly(x**2 + 2*x*y**2 + x*y + 3*y, x, y).terms() [((2, 0), 1), ((1, 2), 2), ((1, 1), 1), ((0, 1), 3)] """ return [ (m, f.rep.dom.to_sympy(c)) for m, c in f.rep.terms(order=order) ]
[docs] def all_coeffs(f): """ Returns all coefficients from a univariate polynomial ``f``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(x**3 + 2*x - 1, x).all_coeffs() [1, 0, 2, -1] """ return [ f.rep.dom.to_sympy(c) for c in f.rep.all_coeffs() ]
[docs] def all_monoms(f): """ Returns all monomials from a univariate polynomial ``f``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(x**3 + 2*x - 1, x).all_monoms() [(3,), (2,), (1,), (0,)] """ return f.rep.all_monoms()
[docs] def all_terms(f): """ Returns all terms from a univariate polynomial ``f``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(x**3 + 2*x - 1, x).all_terms() [((3,), 1), ((2,), 0), ((1,), 2), ((0,), -1)] """ return [ (m, f.rep.dom.to_sympy(c)) for m, c in f.rep.all_terms() ]
[docs] def termwise(f, func, *gens, **args): """ Apply a function to all terms of ``f``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> def func(xxx_todo_changeme, coeff): ... (k,) = xxx_todo_changeme ... return coeff//10**(2-k) >>> Poly(x**2 + 20*x + 400).termwise(func) Poly(x**2 + 2*x + 4, x, domain='ZZ') """ terms = {} for monom, coeff in f.terms(): result = func(monom, coeff) if isinstance(result, tuple): monom, coeff = result else: coeff = result if coeff: if monom not in terms: terms[monom] = coeff else: raise PolynomialError("%s monomial was generated twice" % monom) return f.from_dict(terms, *(gens or f.gens), **args)
[docs] def length(f): """ Returns the number of non-zero terms in ``f``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(x**2 + 2*x - 1).length() 3 """ return len(f.as_dict())
[docs] def as_dict(f, native=False, zero=False): """ Switch to a ``dict`` representation. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x, y >>> Poly(x**2 + 2*x*y**2 - y, x, y).as_dict() {(0, 1): -1, (1, 2): 2, (2, 0): 1} """ if native: return f.rep.to_dict(zero=zero) else: return f.rep.to_sympy_dict(zero=zero)
[docs] def as_list(f, native=False): """Switch to a ``list`` representation. """ if native: return f.rep.to_list() else: return f.rep.to_sympy_list()
[docs] def as_expr(f, *gens): """ Convert a polynomial an expression. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x, y >>> f = Poly(x**2 + 2*x*y**2 - y, x, y) >>> f.as_expr() x**2 + 2*x*y**2 - y >>> f.as_expr({x: 5}) 10*y**2 - y + 25 >>> f.as_expr(5, 6) 379 """ if not gens: gens = f.gens elif len(gens) == 1 and isinstance(gens[0], dict): mapping = gens[0] gens = list(f.gens) for gen, value in mapping.items(): try: index = gens.index(gen) except ValueError: raise GeneratorsError("%s doesn't have %s as generator" % (f, gen)) else: gens[index] = value return basic_from_dict(f.rep.to_sympy_dict(), *gens)
[docs] def lift(f): """ Convert algebraic coefficients to rationals. Examples ======== >>> from sympy import Poly, I >>> from sympy.abc import x >>> Poly(x**2 + I*x + 1, x, extension=I).lift() Poly(x**4 + 3*x**2 + 1, x, domain='QQ') """ if hasattr(f.rep, 'lift'): result = f.rep.lift() else: # pragma: no cover raise OperationNotSupported(f, 'lift') return f.per(result)
[docs] def deflate(f): """ Reduce degree of ``f`` by mapping ``x_i**m`` to ``y_i``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x, y >>> Poly(x**6*y**2 + x**3 + 1, x, y).deflate() ((3, 2), Poly(x**2*y + x + 1, x, y, domain='ZZ')) """ if hasattr(f.rep, 'deflate'): J, result = f.rep.deflate() else: # pragma: no cover raise OperationNotSupported(f, 'deflate') return J, f.per(result)
[docs] def inject(f, front=False): """ Inject ground domain generators into ``f``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x, y >>> f = Poly(x**2*y + x*y**3 + x*y + 1, x) >>> f.inject() Poly(x**2*y + x*y**3 + x*y + 1, x, y, domain='ZZ') >>> f.inject(front=True) Poly(y**3*x + y*x**2 + y*x + 1, y, x, domain='ZZ') """ dom = f.rep.dom if dom.is_Numerical: return f elif not dom.is_Poly: raise DomainError("can't inject generators over %s" % dom) if hasattr(f.rep, 'inject'): result = f.rep.inject(front=front) else: # pragma: no cover raise OperationNotSupported(f, 'inject') if front: gens = dom.gens + f.gens else: gens = f.gens + dom.gens return f.new(result, *gens)
[docs] def eject(f, *gens): """ Eject selected generators into the ground domain. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x, y >>> f = Poly(x**2*y + x*y**3 + x*y + 1, x, y) >>> f.eject(x) Poly(x*y**3 + (x**2 + x)*y + 1, y, domain='ZZ[x]') >>> f.eject(y) Poly(y*x**2 + (y**3 + y)*x + 1, x, domain='ZZ[y]') """ dom = f.rep.dom if not dom.is_Numerical: raise DomainError("can't eject generators over %s" % dom) n, k = len(f.gens), len(gens) if f.gens[:k] == gens: _gens, front = f.gens[n-k:], True elif f.gens[-k:] == gens: _gens, front = f.gens[:n-k], False else: raise NotImplementedError("can only eject front or back generators") dom = dom.inject(*gens) if hasattr(f.rep, 'eject'): result = f.rep.eject(dom, front=front) else: # pragma: no cover raise OperationNotSupported(f, 'eject') return f.new(result, *_gens)
[docs] def terms_gcd(f): """ Remove GCD of terms from the polynomial ``f``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x, y >>> Poly(x**6*y**2 + x**3*y, x, y).terms_gcd() ((3, 1), Poly(x**3*y + 1, x, y, domain='ZZ')) """ if hasattr(f.rep, 'terms_gcd'): J, result = f.rep.terms_gcd() else: # pragma: no cover raise OperationNotSupported(f, 'terms_gcd') return J, f.per(result)
[docs] def add_ground(f, coeff): """ Add an element of the ground domain to ``f``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(x + 1).add_ground(2) Poly(x + 3, x, domain='ZZ') """ if hasattr(f.rep, 'add_ground'): result = f.rep.add_ground(coeff) else: # pragma: no cover raise OperationNotSupported(f, 'add_ground') return f.per(result)
[docs] def sub_ground(f, coeff): """ Subtract an element of the ground domain from ``f``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(x + 1).sub_ground(2) Poly(x - 1, x, domain='ZZ') """ if hasattr(f.rep, 'sub_ground'): result = f.rep.sub_ground(coeff) else: # pragma: no cover raise OperationNotSupported(f, 'sub_ground') return f.per(result)
[docs] def mul_ground(f, coeff): """ Multiply ``f`` by a an element of the ground domain. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(x + 1).mul_ground(2) Poly(2*x + 2, x, domain='ZZ') """ if hasattr(f.rep, 'mul_ground'): result = f.rep.mul_ground(coeff) else: # pragma: no cover raise OperationNotSupported(f, 'mul_ground') return f.per(result)
[docs] def quo_ground(f, coeff): """ Quotient of ``f`` by a an element of the ground domain. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(2*x + 4).quo_ground(2) Poly(x + 2, x, domain='ZZ') >>> Poly(2*x + 3).quo_ground(2) Poly(x + 1, x, domain='ZZ') """ if hasattr(f.rep, 'quo_ground'): result = f.rep.quo_ground(coeff) else: # pragma: no cover raise OperationNotSupported(f, 'quo_ground') return f.per(result)
[docs] def exquo_ground(f, coeff): """ Exact quotient of ``f`` by a an element of the ground domain. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(2*x + 4).exquo_ground(2) Poly(x + 2, x, domain='ZZ') >>> Poly(2*x + 3).exquo_ground(2) Traceback (most recent call last): ... ExactQuotientFailed: 2 does not divide 3 in ZZ """ if hasattr(f.rep, 'exquo_ground'): result = f.rep.exquo_ground(coeff) else: # pragma: no cover raise OperationNotSupported(f, 'exquo_ground') return f.per(result)
[docs] def abs(f): """ Make all coefficients in ``f`` positive. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(x**2 - 1, x).abs() Poly(x**2 + 1, x, domain='ZZ') """ if hasattr(f.rep, 'abs'): result = f.rep.abs() else: # pragma: no cover raise OperationNotSupported(f, 'abs') return f.per(result)
[docs] def neg(f): """ Negate all coefficients in ``f``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(x**2 - 1, x).neg() Poly(-x**2 + 1, x, domain='ZZ') >>> -Poly(x**2 - 1, x) Poly(-x**2 + 1, x, domain='ZZ') """ if hasattr(f.rep, 'neg'): result = f.rep.neg() else: # pragma: no cover raise OperationNotSupported(f, 'neg') return f.per(result)
[docs] def add(f, g): """ Add two polynomials ``f`` and ``g``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(x**2 + 1, x).add(Poly(x - 2, x)) Poly(x**2 + x - 1, x, domain='ZZ') >>> Poly(x**2 + 1, x) + Poly(x - 2, x) Poly(x**2 + x - 1, x, domain='ZZ') """ g = sympify(g) if not g.is_Poly: return f.add_ground(g) _, per, F, G = f._unify(g) if hasattr(f.rep, 'add'): result = F.add(G) else: # pragma: no cover raise OperationNotSupported(f, 'add') return per(result)
[docs] def sub(f, g): """ Subtract two polynomials ``f`` and ``g``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(x**2 + 1, x).sub(Poly(x - 2, x)) Poly(x**2 - x + 3, x, domain='ZZ') >>> Poly(x**2 + 1, x) - Poly(x - 2, x) Poly(x**2 - x + 3, x, domain='ZZ') """ g = sympify(g) if not g.is_Poly: return f.sub_ground(g) _, per, F, G = f._unify(g) if hasattr(f.rep, 'sub'): result = F.sub(G) else: # pragma: no cover raise OperationNotSupported(f, 'sub') return per(result)
[docs] def mul(f, g): """ Multiply two polynomials ``f`` and ``g``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(x**2 + 1, x).mul(Poly(x - 2, x)) Poly(x**3 - 2*x**2 + x - 2, x, domain='ZZ') >>> Poly(x**2 + 1, x)*Poly(x - 2, x) Poly(x**3 - 2*x**2 + x - 2, x, domain='ZZ') """ g = sympify(g) if not g.is_Poly: return f.mul_ground(g) _, per, F, G = f._unify(g) if hasattr(f.rep, 'mul'): result = F.mul(G) else: # pragma: no cover raise OperationNotSupported(f, 'mul') return per(result)
[docs] def sqr(f): """ Square a polynomial ``f``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(x - 2, x).sqr() Poly(x**2 - 4*x + 4, x, domain='ZZ') >>> Poly(x - 2, x)**2 Poly(x**2 - 4*x + 4, x, domain='ZZ') """ if hasattr(f.rep, 'sqr'): result = f.rep.sqr() else: # pragma: no cover raise OperationNotSupported(f, 'sqr') return f.per(result)
[docs] def pow(f, n): """ Raise ``f`` to a non-negative power ``n``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(x - 2, x).pow(3) Poly(x**3 - 6*x**2 + 12*x - 8, x, domain='ZZ') >>> Poly(x - 2, x)**3 Poly(x**3 - 6*x**2 + 12*x - 8, x, domain='ZZ') """ n = int(n) if hasattr(f.rep, 'pow'): result = f.rep.pow(n) else: # pragma: no cover raise OperationNotSupported(f, 'pow') return f.per(result)
[docs] def pdiv(f, g): """ Polynomial pseudo-division of ``f`` by ``g``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(x**2 + 1, x).pdiv(Poly(2*x - 4, x)) (Poly(2*x + 4, x, domain='ZZ'), Poly(20, x, domain='ZZ')) """ _, per, F, G = f._unify(g) if hasattr(f.rep, 'pdiv'): q, r = F.pdiv(G) else: # pragma: no cover raise OperationNotSupported(f, 'pdiv') return per(q), per(r)
[docs] def prem(f, g): """ Polynomial pseudo-remainder of ``f`` by ``g``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(x**2 + 1, x).prem(Poly(2*x - 4, x)) Poly(20, x, domain='ZZ') """ _, per, F, G = f._unify(g) if hasattr(f.rep, 'prem'): result = F.prem(G) else: # pragma: no cover raise OperationNotSupported(f, 'prem') return per(result)
[docs] def pquo(f, g): """ Polynomial pseudo-quotient of ``f`` by ``g``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(x**2 + 1, x).pquo(Poly(2*x - 4, x)) Poly(2*x + 4, x, domain='ZZ') >>> Poly(x**2 - 1, x).pquo(Poly(2*x - 2, x)) Poly(2*x + 2, x, domain='ZZ') """ _, per, F, G = f._unify(g) if hasattr(f.rep, 'pquo'): result = F.pquo(G) else: # pragma: no cover raise OperationNotSupported(f, 'pquo') return per(result)
[docs] def pexquo(f, g): """ Polynomial exact pseudo-quotient of ``f`` by ``g``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(x**2 - 1, x).pexquo(Poly(2*x - 2, x)) Poly(2*x + 2, x, domain='ZZ') >>> Poly(x**2 + 1, x).pexquo(Poly(2*x - 4, x)) Traceback (most recent call last): ... ExactQuotientFailed: 2*x - 4 does not divide x**2 + 1 """ _, per, F, G = f._unify(g) if hasattr(f.rep, 'pexquo'): try: result = F.pexquo(G) except ExactQuotientFailed as exc: raise exc.new(f.as_expr(), g.as_expr()) else: # pragma: no cover raise OperationNotSupported(f, 'pexquo') return per(result)
[docs] def div(f, g, auto=True): """ Polynomial division with remainder of ``f`` by ``g``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(x**2 + 1, x).div(Poly(2*x - 4, x)) (Poly(1/2*x + 1, x, domain='QQ'), Poly(5, x, domain='QQ')) >>> Poly(x**2 + 1, x).div(Poly(2*x - 4, x), auto=False) (Poly(0, x, domain='ZZ'), Poly(x**2 + 1, x, domain='ZZ')) """ dom, per, F, G = f._unify(g) retract = False if auto and dom.has_Ring and not dom.has_Field: F, G = F.to_field(), G.to_field() retract = True if hasattr(f.rep, 'div'): q, r = F.div(G) else: # pragma: no cover raise OperationNotSupported(f, 'div') if retract: try: Q, R = q.to_ring(), r.to_ring() except CoercionFailed: pass else: q, r = Q, R return per(q), per(r)
[docs] def rem(f, g, auto=True): """ Computes the polynomial remainder of ``f`` by ``g``. Examples ======== >>> from sympy import Poly, ZZ, QQ >>> from sympy.abc import x >>> Poly(x**2 + 1, x).rem(Poly(2*x - 4, x)) Poly(5, x, domain='ZZ') >>> Poly(x**2 + 1, x).rem(Poly(2*x - 4, x), auto=False) Poly(x**2 + 1, x, domain='ZZ') """ dom, per, F, G = f._unify(g) retract = False if auto and dom.has_Ring and not dom.has_Field: F, G = F.to_field(), G.to_field() retract = True if hasattr(f.rep, 'rem'): r = F.rem(G) else: # pragma: no cover raise OperationNotSupported(f, 'rem') if retract: try: r = r.to_ring() except CoercionFailed: pass return per(r)
[docs] def quo(f, g, auto=True): """ Computes polynomial quotient of ``f`` by ``g``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(x**2 + 1, x).quo(Poly(2*x - 4, x)) Poly(1/2*x + 1, x, domain='QQ') >>> Poly(x**2 - 1, x).quo(Poly(x - 1, x)) Poly(x + 1, x, domain='ZZ') """ dom, per, F, G = f._unify(g) retract = False if auto and dom.has_Ring and not dom.has_Field: F, G = F.to_field(), G.to_field() retract = True if hasattr(f.rep, 'quo'): q = F.quo(G) else: # pragma: no cover raise OperationNotSupported(f, 'quo') if retract: try: q = q.to_ring() except CoercionFailed: pass return per(q)
[docs] def exquo(f, g, auto=True): """ Computes polynomial exact quotient of ``f`` by ``g``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(x**2 - 1, x).exquo(Poly(x - 1, x)) Poly(x + 1, x, domain='ZZ') >>> Poly(x**2 + 1, x).exquo(Poly(2*x - 4, x)) Traceback (most recent call last): ... ExactQuotientFailed: 2*x - 4 does not divide x**2 + 1 """ dom, per, F, G = f._unify(g) retract = False if auto and dom.has_Ring and not dom.has_Field: F, G = F.to_field(), G.to_field() retract = True if hasattr(f.rep, 'exquo'): try: q = F.exquo(G) except ExactQuotientFailed as exc: raise exc.new(f.as_expr(), g.as_expr()) else: # pragma: no cover raise OperationNotSupported(f, 'exquo') if retract: try: q = q.to_ring() except CoercionFailed: pass return per(q)
def _gen_to_level(f, gen): """Returns level associated with the given generator. """ if isinstance(gen, int): length = len(f.gens) if -length <= gen < length: if gen < 0: return length + gen else: return gen else: raise PolynomialError("-%s <= gen < %s expected, got %s" % (length, length, gen)) else: try: return list(f.gens).index(sympify(gen)) except ValueError: raise PolynomialError("a valid generator expected, got %s" % gen)
[docs] def degree(f, gen=0): """ Returns degree of ``f`` in ``x_j``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x, y >>> Poly(x**2 + y*x + 1, x, y).degree() 2 >>> Poly(x**2 + y*x + y, x, y).degree(y) 1 """ j = f._gen_to_level(gen) if hasattr(f.rep, 'degree'): return f.rep.degree(j) else: # pragma: no cover raise OperationNotSupported(f, 'degree')
[docs] def degree_list(f): """ Returns a list of degrees of ``f``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x, y >>> Poly(x**2 + y*x + 1, x, y).degree_list() (2, 1) """ if hasattr(f.rep, 'degree_list'): return f.rep.degree_list() else: # pragma: no cover raise OperationNotSupported(f, 'degree_list')
[docs] def total_degree(f): """ Returns the total degree of ``f``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x, y >>> Poly(x**2 + y*x + 1, x, y).total_degree() 2 >>> Poly(x + y**5, x, y).total_degree() 5 """ if hasattr(f.rep, 'total_degree'): return f.rep.total_degree() else: # pragma: no cover raise OperationNotSupported(f, 'total_degree')
[docs] def homogeneous_order(f): """ Returns the homogeneous order of ``f``. A homogeneous polynomial is a polynomial whose all monomials with non-zero coefficients have the same total degree. This degree is the homogeneous order of ``f``. If you only want to check if a polynomial is homogeneous, then use :func:`Poly.is_homogeneous`. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x, y >>> f = Poly(x**5 + 2*x**3*y**2 + 9*x*y**4) >>> f.homogeneous_order() 5 """ if hasattr(f.rep, 'homogeneous_order'): return f.rep.homogeneous_order() else: # pragma: no cover raise OperationNotSupported(f, 'homogeneous_order')
[docs] def LC(f, order=None): """ Returns the leading coefficient of ``f``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(4*x**3 + 2*x**2 + 3*x, x).LC() 4 """ if order is not None: return f.coeffs(order)[0] if hasattr(f.rep, 'LC'): result = f.rep.LC() else: # pragma: no cover raise OperationNotSupported(f, 'LC') return f.rep.dom.to_sympy(result)
[docs] def TC(f): """ Returns the trailing coefficient of ``f``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(x**3 + 2*x**2 + 3*x, x).TC() 0 """ if hasattr(f.rep, 'TC'): result = f.rep.TC() else: # pragma: no cover raise OperationNotSupported(f, 'TC') return f.rep.dom.to_sympy(result)
[docs] def EC(f, order=None): """ Returns the last non-zero coefficient of ``f``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(x**3 + 2*x**2 + 3*x, x).EC() 3 """ if hasattr(f.rep, 'coeffs'): return f.coeffs(order)[-1] else: # pragma: no cover raise OperationNotSupported(f, 'EC')
[docs] def nth(f, *N): """ Returns the ``n``-th coefficient of ``f``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x, y >>> Poly(x**3 + 2*x**2 + 3*x, x).nth(2) 2 >>> Poly(x**3 + 2*x*y**2 + y**2, x, y).nth(1, 2) 2 """ if hasattr(f.rep, 'nth'): result = f.rep.nth(*list(map(int, N))) else: # pragma: no cover raise OperationNotSupported(f, 'nth') return f.rep.dom.to_sympy(result)
[docs] def LM(f, order=None): """ Returns the leading monomial of ``f``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x, y >>> Poly(4*x**2 + 2*x*y**2 + x*y + 3*y, x, y).LM() x**2*y**0 """ return Monomial(f.monoms(order)[0], f.gens)
[docs] def EM(f, order=None): """ Returns the last non-zero monomial of ``f``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x, y >>> Poly(4*x**2 + 2*x*y**2 + x*y + 3*y, x, y).EM() x**0*y**1 """ return Monomial(f.monoms(order)[-1], f.gens)
[docs] def LT(f, order=None): """ Returns the leading term of ``f``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x, y >>> Poly(4*x**2 + 2*x*y**2 + x*y + 3*y, x, y).LT() (x**2*y**0, 4) """ monom, coeff = f.terms(order)[0] return Monomial(monom, f.gens), coeff
[docs] def ET(f, order=None): """ Returns the last non-zero term of ``f``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x, y >>> Poly(4*x**2 + 2*x*y**2 + x*y + 3*y, x, y).ET() (x**0*y**1, 3) """ monom, coeff = f.terms(order)[-1] return Monomial(monom, f.gens), coeff
[docs] def max_norm(f): """ Returns maximum norm of ``f``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(-x**2 + 2*x - 3, x).max_norm() 3 """ if hasattr(f.rep, 'max_norm'): result = f.rep.max_norm() else: # pragma: no cover raise OperationNotSupported(f, 'max_norm') return f.rep.dom.to_sympy(result)
[docs] def l1_norm(f): """ Returns l1 norm of ``f``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(-x**2 + 2*x - 3, x).l1_norm() 6 """ if hasattr(f.rep, 'l1_norm'): result = f.rep.l1_norm() else: # pragma: no cover raise OperationNotSupported(f, 'l1_norm') return f.rep.dom.to_sympy(result)
[docs] def clear_denoms(f, convert=False): """ Clear denominators, but keep the ground domain. Examples ======== >>> from sympy import Poly, S, QQ >>> from sympy.abc import x >>> f = Poly(x/2 + S(1)/3, x, domain=QQ) >>> f.clear_denoms() (6, Poly(3*x + 2, x, domain='QQ')) >>> f.clear_denoms(convert=True) (6, Poly(3*x + 2, x, domain='ZZ')) """ if not f.rep.dom.has_Field: return S.One, f dom = f.rep.dom.get_ring() if hasattr(f.rep, 'clear_denoms'): coeff, result = f.rep.clear_denoms() else: # pragma: no cover raise OperationNotSupported(f, 'clear_denoms') coeff, f = dom.to_sympy(coeff), f.per(result) if not convert: return coeff, f else: return coeff, f.to_ring()
[docs] def rat_clear_denoms(f, g): """ Clear denominators in a rational function ``f/g``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x, y >>> f = Poly(x**2/y + 1, x) >>> g = Poly(x**3 + y, x) >>> p, q = f.rat_clear_denoms(g) >>> p Poly(x**2 + y, x, domain='ZZ[y]') >>> q Poly(y*x**3 + y**2, x, domain='ZZ[y]') """ dom, per, f, g = f._unify(g) f = per(f) g = per(g) if not (dom.has_Field and dom.has_assoc_Ring): return f, g a, f = f.clear_denoms(convert=True) b, g = g.clear_denoms(convert=True) f = f.mul_ground(b) g = g.mul_ground(a) return f, g
[docs] def integrate(f, *specs, **args): """ Computes indefinite integral of ``f``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x, y >>> Poly(x**2 + 2*x + 1, x).integrate() Poly(1/3*x**3 + x**2 + x, x, domain='QQ') >>> Poly(x*y**2 + x, x, y).integrate((0, 1), (1, 0)) Poly(1/2*x**2*y**2 + 1/2*x**2, x, y, domain='QQ') """ if args.get('auto', True) and f.rep.dom.has_Ring: f = f.to_field() if hasattr(f.rep, 'integrate'): if not specs: return f.per(f.rep.integrate(m=1)) rep = f.rep for spec in specs: if type(spec) is tuple: gen, m = spec else: gen, m = spec, 1 rep = rep.integrate(int(m), f._gen_to_level(gen)) return f.per(rep) else: # pragma: no cover raise OperationNotSupported(f, 'integrate')
[docs] def diff(f, *specs): """ Computes partial derivative of ``f``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x, y >>> Poly(x**2 + 2*x + 1, x).diff() Poly(2*x + 2, x, domain='ZZ') >>> Poly(x*y**2 + x, x, y).diff((0, 0), (1, 1)) Poly(2*x*y, x, y, domain='ZZ') """ if hasattr(f.rep, 'diff'): if not specs: return f.per(f.rep.diff(m=1)) rep = f.rep for spec in specs: if type(spec) is tuple: gen, m = spec else: gen, m = spec, 1 rep = rep.diff(int(m), f._gen_to_level(gen)) return f.per(rep) else: # pragma: no cover raise OperationNotSupported(f, 'diff')
[docs] def eval(f, x, a=None, auto=True): """ Evaluate ``f`` at ``a`` in the given variable. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x, y, z >>> Poly(x**2 + 2*x + 3, x).eval(2) 11 >>> Poly(2*x*y + 3*x + y + 2, x, y).eval(x, 2) Poly(5*y + 8, y, domain='ZZ') >>> f = Poly(2*x*y + 3*x + y + 2*z, x, y, z) >>> f.eval({x: 2}) Poly(5*y + 2*z + 6, y, z, domain='ZZ') >>> f.eval({x: 2, y: 5}) Poly(2*z + 31, z, domain='ZZ') >>> f.eval({x: 2, y: 5, z: 7}) 45 >>> f.eval((2, 5)) Poly(2*z + 31, z, domain='ZZ') >>> f(2, 5) Poly(2*z + 31, z, domain='ZZ') """ if a is None: if isinstance(x, dict): mapping = x for gen, value in mapping.items(): f = f.eval(gen, value) return f elif isinstance(x, (tuple, list)): values = x if len(values) > len(f.gens): raise ValueError("too many values provided") for gen, value in zip(f.gens, values): f = f.eval(gen, value) return f else: j, a = 0, x else: j = f._gen_to_level(x) if not hasattr(f.rep, 'eval'): # pragma: no cover raise OperationNotSupported(f, 'eval') try: result = f.rep.eval(a, j) except CoercionFailed: if not auto: raise DomainError("can't evaluate at %s in %s" % (a, f.rep.dom)) else: domain, [a] = construct_domain([a]) f = f.set_domain(domain) result = f.rep.eval(a, j) return f.per(result, remove=j)
def __call__(f, *values): """ Evaluate ``f`` at the give values. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x, y, z >>> f = Poly(2*x*y + 3*x + y + 2*z, x, y, z) >>> f(2) Poly(5*y + 2*z + 6, y, z, domain='ZZ') >>> f(2, 5) Poly(2*z + 31, z, domain='ZZ') >>> f(2, 5, 7) 45 """ return f.eval(values)
[docs] def half_gcdex(f, g, auto=True): """ Half extended Euclidean algorithm of ``f`` and ``g``. Returns ``(s, h)`` such that ``h = gcd(f, g)`` and ``s*f = h (mod g)``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> f = x**4 - 2*x**3 - 6*x**2 + 12*x + 15 >>> g = x**3 + x**2 - 4*x - 4 >>> Poly(f).half_gcdex(Poly(g)) (Poly(-1/5*x + 3/5, x, domain='QQ'), Poly(x + 1, x, domain='QQ')) """ dom, per, F, G = f._unify(g) if auto and dom.has_Ring: F, G = F.to_field(), G.to_field() if hasattr(f.rep, 'half_gcdex'): s, h = F.half_gcdex(G) else: # pragma: no cover raise OperationNotSupported(f, 'half_gcdex') return per(s), per(h)
[docs] def gcdex(f, g, auto=True): """ Extended Euclidean algorithm of ``f`` and ``g``. Returns ``(s, t, h)`` such that ``h = gcd(f, g)`` and ``s*f + t*g = h``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> f = x**4 - 2*x**3 - 6*x**2 + 12*x + 15 >>> g = x**3 + x**2 - 4*x - 4 >>> Poly(f).gcdex(Poly(g)) (Poly(-1/5*x + 3/5, x, domain='QQ'), Poly(1/5*x**2 - 6/5*x + 2, x, domain='QQ'), Poly(x + 1, x, domain='QQ')) """ dom, per, F, G = f._unify(g) if auto and dom.has_Ring: F, G = F.to_field(), G.to_field() if hasattr(f.rep, 'gcdex'): s, t, h = F.gcdex(G) else: # pragma: no cover raise OperationNotSupported(f, 'gcdex') return per(s), per(t), per(h)
[docs] def invert(f, g, auto=True): """ Invert ``f`` modulo ``g`` when possible. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(x**2 - 1, x).invert(Poly(2*x - 1, x)) Poly(-4/3, x, domain='QQ') >>> Poly(x**2 - 1, x).invert(Poly(x - 1, x)) Traceback (most recent call last): ... NotInvertible: zero divisor """ dom, per, F, G = f._unify(g) if auto and dom.has_Ring: F, G = F.to_field(), G.to_field() if hasattr(f.rep, 'invert'): result = F.invert(G) else: # pragma: no cover raise OperationNotSupported(f, 'invert') return per(result)
[docs] def revert(f, n): """Compute ``f**(-1)`` mod ``x**n``. """ if hasattr(f.rep, 'revert'): result = f.rep.revert(int(n)) else: # pragma: no cover raise OperationNotSupported(f, 'revert') return f.per(result)
[docs] def subresultants(f, g): """ Computes the subresultant PRS sequence of ``f`` and ``g``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(x**2 + 1, x).subresultants(Poly(x**2 - 1, x)) [Poly(x**2 + 1, x, domain='ZZ'), Poly(x**2 - 1, x, domain='ZZ'), Poly(-2, x, domain='ZZ')] """ _, per, F, G = f._unify(g) if hasattr(f.rep, 'subresultants'): result = F.subresultants(G) else: # pragma: no cover raise OperationNotSupported(f, 'subresultants') return list(map(per, result))
[docs] def resultant(f, g): """ Computes the resultant of ``f`` and ``g`` via PRS. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(x**2 + 1, x).resultant(Poly(x**2 - 1, x)) 4 """ _, per, F, G = f._unify(g) if hasattr(f.rep, 'resultant'): result = F.resultant(G) else: # pragma: no cover raise OperationNotSupported(f, 'resultant') return per(result, remove=0)
[docs] def discriminant(f): """ Computes the discriminant of ``f``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(x**2 + 2*x + 3, x).discriminant() -8 """ if hasattr(f.rep, 'discriminant'): result = f.rep.discriminant() else: # pragma: no cover raise OperationNotSupported(f, 'discriminant') return f.per(result, remove=0)
[docs] def cofactors(f, g): """ Returns the GCD of ``f`` and ``g`` and their cofactors. Returns polynomials ``(h, cff, cfg)`` such that ``h = gcd(f, g)``, and ``cff = quo(f, h)`` and ``cfg = quo(g, h)`` are, so called, cofactors of ``f`` and ``g``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(x**2 - 1, x).cofactors(Poly(x**2 - 3*x + 2, x)) (Poly(x - 1, x, domain='ZZ'), Poly(x + 1, x, domain='ZZ'), Poly(x - 2, x, domain='ZZ')) """ _, per, F, G = f._unify(g) if hasattr(f.rep, 'cofactors'): h, cff, cfg = F.cofactors(G) else: # pragma: no cover raise OperationNotSupported(f, 'cofactors') return per(h), per(cff), per(cfg)
[docs] def gcd(f, g): """ Returns the polynomial GCD of ``f`` and ``g``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(x**2 - 1, x).gcd(Poly(x**2 - 3*x + 2, x)) Poly(x - 1, x, domain='ZZ') """ _, per, F, G = f._unify(g) if hasattr(f.rep, 'gcd'): result = F.gcd(G) else: # pragma: no cover raise OperationNotSupported(f, 'gcd') return per(result)
[docs] def lcm(f, g): """ Returns polynomial LCM of ``f`` and ``g``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(x**2 - 1, x).lcm(Poly(x**2 - 3*x + 2, x)) Poly(x**3 - 2*x**2 - x + 2, x, domain='ZZ') """ _, per, F, G = f._unify(g) if hasattr(f.rep, 'lcm'): result = F.lcm(G) else: # pragma: no cover raise OperationNotSupported(f, 'lcm') return per(result)
[docs] def trunc(f, p): """ Reduce ``f`` modulo a constant ``p``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(2*x**3 + 3*x**2 + 5*x + 7, x).trunc(3) Poly(-x**3 - x + 1, x, domain='ZZ') """ p = f.rep.dom.convert(p) if hasattr(f.rep, 'trunc'): result = f.rep.trunc(p) else: # pragma: no cover raise OperationNotSupported(f, 'trunc') return f.per(result)
[docs] def monic(f, auto=True): """ Divides all coefficients by ``LC(f)``. Examples ======== >>> from sympy import Poly, ZZ >>> from sympy.abc import x >>> Poly(3*x**2 + 6*x + 9, x, domain=ZZ).monic() Poly(x**2 + 2*x + 3, x, domain='QQ') >>> Poly(3*x**2 + 4*x + 2, x, domain=ZZ).monic() Poly(x**2 + 4/3*x + 2/3, x, domain='QQ') """ if auto and f.rep.dom.has_Ring: f = f.to_field() if hasattr(f.rep, 'monic'): result = f.rep.monic() else: # pragma: no cover raise OperationNotSupported(f, 'monic') return f.per(result)
[docs] def content(f): """ Returns the GCD of polynomial coefficients. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(6*x**2 + 8*x + 12, x).content() 2 """ if hasattr(f.rep, 'content'): result = f.rep.content() else: # pragma: no cover raise OperationNotSupported(f, 'content') return f.rep.dom.to_sympy(result)
[docs] def primitive(f): """ Returns the content and a primitive form of ``f``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(2*x**2 + 8*x + 12, x).primitive() (2, Poly(x**2 + 4*x + 6, x, domain='ZZ')) """ if hasattr(f.rep, 'primitive'): cont, result = f.rep.primitive() else: # pragma: no cover raise OperationNotSupported(f, 'primitive') return f.rep.dom.to_sympy(cont), f.per(result)
[docs] def compose(f, g): """ Computes the functional composition of ``f`` and ``g``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(x**2 + x, x).compose(Poly(x - 1, x)) Poly(x**2 - x, x, domain='ZZ') """ _, per, F, G = f._unify(g) if hasattr(f.rep, 'compose'): result = F.compose(G) else: # pragma: no cover raise OperationNotSupported(f, 'compose') return per(result)
[docs] def decompose(f): """ Computes a functional decomposition of ``f``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(x**4 + 2*x**3 - x - 1, x, domain='ZZ').decompose() [Poly(x**2 - x - 1, x, domain='ZZ'), Poly(x**2 + x, x, domain='ZZ')] """ if hasattr(f.rep, 'decompose'): result = f.rep.decompose() else: # pragma: no cover raise OperationNotSupported(f, 'decompose') return list(map(f.per, result))
[docs] def shift(f, a): """ Efficiently compute Taylor shift ``f(x + a)``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(x**2 - 2*x + 1, x).shift(2) Poly(x**2 + 2*x + 1, x, domain='ZZ') """ if hasattr(f.rep, 'shift'): result = f.rep.shift(a) else: # pragma: no cover raise OperationNotSupported(f, 'shift') return f.per(result)
[docs] def sturm(f, auto=True): """ Computes the Sturm sequence of ``f``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(x**3 - 2*x**2 + x - 3, x).sturm() [Poly(x**3 - 2*x**2 + x - 3, x, domain='QQ'), Poly(3*x**2 - 4*x + 1, x, domain='QQ'), Poly(2/9*x + 25/9, x, domain='QQ'), Poly(-2079/4, x, domain='QQ')] """ if auto and f.rep.dom.has_Ring: f = f.to_field() if hasattr(f.rep, 'sturm'): result = f.rep.sturm() else: # pragma: no cover raise OperationNotSupported(f, 'sturm') return list(map(f.per, result))
[docs] def gff_list(f): """ Computes greatest factorial factorization of ``f``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> f = x**5 + 2*x**4 - x**3 - 2*x**2 >>> Poly(f).gff_list() [(Poly(x, x, domain='ZZ'), 1), (Poly(x + 2, x, domain='ZZ'), 4)] """ if hasattr(f.rep, 'gff_list'): result = f.rep.gff_list() else: # pragma: no cover raise OperationNotSupported(f, 'gff_list') return [ (f.per(g), k) for g, k in result ]
[docs] def sqf_norm(f): """ Computes square-free norm of ``f``. Returns ``s``, ``f``, ``r``, such that ``g(x) = f(x-sa)`` and ``r(x) = Norm(g(x))`` is a square-free polynomial over ``K``, where ``a`` is the algebraic extension of the ground domain. Examples ======== >>> from sympy import Poly, sqrt >>> from sympy.abc import x >>> s, f, r = Poly(x**2 + 1, x, extension=[sqrt(3)]).sqf_norm() >>> s 1 >>> f Poly(x**2 - 2*sqrt(3)*x + 4, x, domain='QQ<sqrt(3)>') >>> r Poly(x**4 - 4*x**2 + 16, x, domain='QQ') """ if hasattr(f.rep, 'sqf_norm'): s, g, r = f.rep.sqf_norm() else: # pragma: no cover raise OperationNotSupported(f, 'sqf_norm') return s, f.per(g), f.per(r)
[docs] def sqf_part(f): """ Computes square-free part of ``f``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(x**3 - 3*x - 2, x).sqf_part() Poly(x**2 - x - 2, x, domain='ZZ') """ if hasattr(f.rep, 'sqf_part'): result = f.rep.sqf_part() else: # pragma: no cover raise OperationNotSupported(f, 'sqf_part') return f.per(result)
[docs] def sqf_list(f, all=False): """ Returns a list of square-free factors of ``f``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> f = 2*x**5 + 16*x**4 + 50*x**3 + 76*x**2 + 56*x + 16 >>> Poly(f).sqf_list() (2, [(Poly(x + 1, x, domain='ZZ'), 2), (Poly(x + 2, x, domain='ZZ'), 3)]) >>> Poly(f).sqf_list(all=True) (2, [(Poly(1, x, domain='ZZ'), 1), (Poly(x + 1, x, domain='ZZ'), 2), (Poly(x + 2, x, domain='ZZ'), 3)]) """ if hasattr(f.rep, 'sqf_list'): coeff, factors = f.rep.sqf_list(all) else: # pragma: no cover raise OperationNotSupported(f, 'sqf_list') return f.rep.dom.to_sympy(coeff), [ (f.per(g), k) for g, k in factors ]
[docs] def sqf_list_include(f, all=False): """ Returns a list of square-free factors of ``f``. Examples ======== >>> from sympy import Poly, expand >>> from sympy.abc import x >>> f = expand(2*(x + 1)**3*x**4) >>> f 2*x**7 + 6*x**6 + 6*x**5 + 2*x**4 >>> Poly(f).sqf_list_include() [(Poly(2, x, domain='ZZ'), 1), (Poly(x + 1, x, domain='ZZ'), 3), (Poly(x, x, domain='ZZ'), 4)] >>> Poly(f).sqf_list_include(all=True) [(Poly(2, x, domain='ZZ'), 1), (Poly(1, x, domain='ZZ'), 2), (Poly(x + 1, x, domain='ZZ'), 3), (Poly(x, x, domain='ZZ'), 4)] """ if hasattr(f.rep, 'sqf_list_include'): factors = f.rep.sqf_list_include(all) else: # pragma: no cover raise OperationNotSupported(f, 'sqf_list_include') return [ (f.per(g), k) for g, k in factors ]
[docs] def factor_list(f): """ Returns a list of irreducible factors of ``f``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x, y >>> f = 2*x**5 + 2*x**4*y + 4*x**3 + 4*x**2*y + 2*x + 2*y >>> Poly(f).factor_list() (2, [(Poly(x + y, x, y, domain='ZZ'), 1), (Poly(x**2 + 1, x, y, domain='ZZ'), 2)]) """ if hasattr(f.rep, 'factor_list'): try: coeff, factors = f.rep.factor_list() except DomainError: return S.One, [(f, 1)] else: # pragma: no cover raise OperationNotSupported(f, 'factor_list') return f.rep.dom.to_sympy(coeff), [ (f.per(g), k) for g, k in factors ]
[docs] def factor_list_include(f): """ Returns a list of irreducible factors of ``f``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x, y >>> f = 2*x**5 + 2*x**4*y + 4*x**3 + 4*x**2*y + 2*x + 2*y >>> Poly(f).factor_list_include() [(Poly(2*x + 2*y, x, y, domain='ZZ'), 1), (Poly(x**2 + 1, x, y, domain='ZZ'), 2)] """ if hasattr(f.rep, 'factor_list_include'): try: factors = f.rep.factor_list_include() except DomainError: return [(f, 1)] else: # pragma: no cover raise OperationNotSupported(f, 'factor_list_include') return [ (f.per(g), k) for g, k in factors ]
[docs] def intervals(f, all=False, eps=None, inf=None, sup=None, fast=False, sqf=False): """ Compute isolating intervals for roots of ``f``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(x**2 - 3, x).intervals() [((-2, -1), 1), ((1, 2), 1)] >>> Poly(x**2 - 3, x).intervals(eps=1e-2) [((-26/15, -19/11), 1), ((19/11, 26/15), 1)] """ if eps is not None: eps = QQ.convert(eps) if eps <= 0: raise ValueError("'eps' must be a positive rational") if inf is not None: inf = QQ.convert(inf) if sup is not None: sup = QQ.convert(sup) if hasattr(f.rep, 'intervals'): result = f.rep.intervals(all=all, eps=eps, inf=inf, sup=sup, fast=fast, sqf=sqf) else: # pragma: no cover raise OperationNotSupported(f, 'intervals') if sqf: def _real(interval): s, t = interval return (QQ.to_sympy(s), QQ.to_sympy(t)) if not all: return list(map(_real, result)) def _complex(rectangle): (u, v), (s, t) = rectangle return (QQ.to_sympy(u) + I*QQ.to_sympy(v), QQ.to_sympy(s) + I*QQ.to_sympy(t)) real_part, complex_part = result return list(map(_real, real_part)), list(map(_complex, complex_part)) else: def _real(interval): (s, t), k = interval return ((QQ.to_sympy(s), QQ.to_sympy(t)), k) if not all: return list(map(_real, result)) def _complex(rectangle): ((u, v), (s, t)), k = rectangle return ((QQ.to_sympy(u) + I*QQ.to_sympy(v), QQ.to_sympy(s) + I*QQ.to_sympy(t)), k) real_part, complex_part = result return list(map(_real, real_part)), list(map(_complex, complex_part))
[docs] def refine_root(f, s, t, eps=None, steps=None, fast=False, check_sqf=False): """ Refine an isolating interval of a root to the given precision. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(x**2 - 3, x).refine_root(1, 2, eps=1e-2) (19/11, 26/15) """ if check_sqf and not f.is_sqf: raise PolynomialError("only square-free polynomials supported") s, t = QQ.convert(s), QQ.convert(t) if eps is not None: eps = QQ.convert(eps) if eps <= 0: raise ValueError("'eps' must be a positive rational") if steps is not None: steps = int(steps) elif eps is None: steps = 1 if hasattr(f.rep, 'refine_root'): S, T = f.rep.refine_root(s, t, eps=eps, steps=steps, fast=fast) else: # pragma: no cover raise OperationNotSupported(f, 'refine_root') return QQ.to_sympy(S), QQ.to_sympy(T)
[docs] def count_roots(f, inf=None, sup=None): """ Return the number of roots of ``f`` in ``[inf, sup]`` interval. Examples ======== >>> from sympy import Poly, I >>> from sympy.abc import x >>> Poly(x**4 - 4, x).count_roots(-3, 3) 2 >>> Poly(x**4 - 4, x).count_roots(0, 1 + 3*I) 1 """ inf_real, sup_real = True, True if inf is not None: inf = sympify(inf) if inf is S.NegativeInfinity: inf = None else: re, im = inf.as_real_imag() if not im: inf = QQ.convert(inf) else: inf, inf_real = list(map(QQ.convert, (re, im))), False if sup is not None: sup = sympify(sup) if sup is S.Infinity: sup = None else: re, im = sup.as_real_imag() if not im: sup = QQ.convert(sup) else: sup, sup_real = list(map(QQ.convert, (re, im))), False if inf_real and sup_real: if hasattr(f.rep, 'count_real_roots'): count = f.rep.count_real_roots(inf=inf, sup=sup) else: # pragma: no cover raise OperationNotSupported(f, 'count_real_roots') else: if inf_real and inf is not None: inf = (inf, QQ.zero) if sup_real and sup is not None: sup = (sup, QQ.zero) if hasattr(f.rep, 'count_complex_roots'): count = f.rep.count_complex_roots(inf=inf, sup=sup) else: # pragma: no cover raise OperationNotSupported(f, 'count_complex_roots') return Integer(count)
[docs] def root(f, index, radicals=True): """ Get an indexed root of a polynomial. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> f = Poly(2*x**3 - 7*x**2 + 4*x + 4) >>> f.root(0) -1/2 >>> f.root(1) 2 >>> f.root(2) 2 >>> f.root(3) Traceback (most recent call last): ... IndexError: root index out of [-3, 2] range, got 3 >>> Poly(x**5 + x + 1).root(0) RootOf(x**3 - x**2 + 1, 0) """ return sympy.polys.rootoftools.RootOf(f, index, radicals=radicals)
[docs] def real_roots(f, multiple=True, radicals=True): """ Return a list of real roots with multiplicities. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(2*x**3 - 7*x**2 + 4*x + 4).real_roots() [-1/2, 2, 2] >>> Poly(x**3 + x + 1).real_roots() [RootOf(x**3 + x + 1, 0)] """ reals = sympy.polys.rootoftools.RootOf.real_roots(f, radicals=radicals) if multiple: return reals else: return group(reals, multiple=False)
[docs] def all_roots(f, multiple=True, radicals=True): """ Return a list of real and complex roots with multiplicities. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(2*x**3 - 7*x**2 + 4*x + 4).all_roots() [-1/2, 2, 2] >>> Poly(x**3 + x + 1).all_roots() [RootOf(x**3 + x + 1, 0), RootOf(x**3 + x + 1, 1), RootOf(x**3 + x + 1, 2)] """ roots = sympy.polys.rootoftools.RootOf.all_roots(f, radicals=radicals) if multiple: return roots else: return group(roots, multiple=False)
[docs] def nroots(f, n=15, maxsteps=50, cleanup=True, error=False): """ Compute numerical approximations of roots of ``f``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(x**2 - 3).nroots(n=15) [-1.73205080756888, 1.73205080756888] >>> Poly(x**2 - 3).nroots(n=30) [-1.73205080756887729352744634151, 1.73205080756887729352744634151] """ if f.is_multivariate: raise MultivariatePolynomialError("can't compute numerical roots of %s" % f) if f.degree() <= 0: return [] coeffs = [ coeff.evalf(n=n).as_real_imag() for coeff in f.all_coeffs() ] dps = sympy.mpmath.mp.dps sympy.mpmath.mp.dps = n try: try: coeffs = [ sympy.mpmath.mpc(*coeff) for coeff in coeffs ] except TypeError: raise DomainError("numerical domain expected, got %s" % f.rep.dom) result = sympy.mpmath.polyroots(coeffs, maxsteps=maxsteps, cleanup=cleanup, error=error) if error: roots, error = result else: roots, error = result, None roots = list(map(sympify, sorted(roots, key=lambda r: (r.real, r.imag)))) finally: sympy.mpmath.mp.dps = dps if error is not None: return roots, sympify(error) else: return roots
[docs] def ground_roots(f): """ Compute roots of ``f`` by factorization in the ground domain. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(x**6 - 4*x**4 + 4*x**3 - x**2).ground_roots() {0: 2, 1: 2} """ if f.is_multivariate: raise MultivariatePolynomialError("can't compute ground roots of %s" % f) roots = {} for factor, k in f.factor_list()[1]: if factor.is_linear: a, b = factor.all_coeffs() roots[-b/a] = k return roots
[docs] def nth_power_roots_poly(f, n): """ Construct a polynomial with n-th powers of roots of ``f``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> f = Poly(x**4 - x**2 + 1) >>> f.nth_power_roots_poly(2) Poly(x**4 - 2*x**3 + 3*x**2 - 2*x + 1, x, domain='ZZ') >>> f.nth_power_roots_poly(3) Poly(x**4 + 2*x**2 + 1, x, domain='ZZ') >>> f.nth_power_roots_poly(4) Poly(x**4 + 2*x**3 + 3*x**2 + 2*x + 1, x, domain='ZZ') >>> f.nth_power_roots_poly(12) Poly(x**4 - 4*x**3 + 6*x**2 - 4*x + 1, x, domain='ZZ') """ if f.is_multivariate: raise MultivariatePolynomialError("must be a univariate polynomial") N = sympify(n) if N.is_Integer and N >= 1: n = int(N) else: raise ValueError("'n' must an integer and n >= 1, got %s" % n) x = f.gen t = Dummy('t') r = f.resultant(f.__class__.from_expr(x**n - t, x, t)) return r.replace(t, x)
[docs] def cancel(f, g, include=False): """ Cancel common factors in a rational function ``f/g``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(2*x**2 - 2, x).cancel(Poly(x**2 - 2*x + 1, x)) (1, Poly(2*x + 2, x, domain='ZZ'), Poly(x - 1, x, domain='ZZ')) >>> Poly(2*x**2 - 2, x).cancel(Poly(x**2 - 2*x + 1, x), include=True) (Poly(2*x + 2, x, domain='ZZ'), Poly(x - 1, x, domain='ZZ')) """ dom, per, F, G = f._unify(g) if hasattr(F, 'cancel'): result = F.cancel(G, include=include) else: # pragma: no cover raise OperationNotSupported(f, 'cancel') if not include: if dom.has_assoc_Ring: dom = dom.get_ring() cp, cq, p, q = result cp = dom.to_sympy(cp) cq = dom.to_sympy(cq) return cp/cq, per(p), per(q) else: return tuple(map(per, result))
@property
[docs] def is_zero(f): """ Returns ``True`` if ``f`` is a zero polynomial. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(0, x).is_zero True >>> Poly(1, x).is_zero False """ return f.rep.is_zero
@property
[docs] def is_one(f): """ Returns ``True`` if ``f`` is a unit polynomial. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(0, x).is_one False >>> Poly(1, x).is_one True """ return f.rep.is_one
@property
[docs] def is_sqf(f): """ Returns ``True`` if ``f`` is a square-free polynomial. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(x**2 - 2*x + 1, x).is_sqf False >>> Poly(x**2 - 1, x).is_sqf True """ return f.rep.is_sqf
@property
[docs] def is_monic(f): """ Returns ``True`` if the leading coefficient of ``f`` is one. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(x + 2, x).is_monic True >>> Poly(2*x + 2, x).is_monic False """ return f.rep.is_monic
@property
[docs] def is_primitive(f): """ Returns ``True`` if GCD of the coefficients of ``f`` is one. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(2*x**2 + 6*x + 12, x).is_primitive False >>> Poly(x**2 + 3*x + 6, x).is_primitive True """ return f.rep.is_primitive
@property
[docs] def is_ground(f): """ Returns ``True`` if ``f`` is an element of the ground domain. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x, y >>> Poly(x, x).is_ground False >>> Poly(2, x).is_ground True >>> Poly(y, x).is_ground True """ return f.rep.is_ground
@property
[docs] def is_linear(f): """ Returns ``True`` if ``f`` is linear in all its variables. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x, y >>> Poly(x + y + 2, x, y).is_linear True >>> Poly(x*y + 2, x, y).is_linear False """ return f.rep.is_linear
@property
[docs] def is_quadratic(f): """ Returns ``True`` if ``f`` is quadratic in all its variables. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x, y >>> Poly(x*y + 2, x, y).is_quadratic True >>> Poly(x*y**2 + 2, x, y).is_quadratic False """ return f.rep.is_quadratic
@property
[docs] def is_monomial(f): """ Returns ``True`` if ``f`` is zero or has only one term. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(3*x**2, x).is_monomial True >>> Poly(3*x**2 + 1, x).is_monomial False """ return f.rep.is_monomial
@property
[docs] def is_homogeneous(f): """ Returns ``True`` if ``f`` is a homogeneous polynomial. A homogeneous polynomial is a polynomial whose all monomials with non-zero coefficients have the same total degree. If you want not only to check if a polynomial is homogeneous but also compute its homogeneous order, then use :func:`Poly.homogeneous_order`. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x, y >>> Poly(x**2 + x*y, x, y).is_homogeneous True >>> Poly(x**3 + x*y, x, y).is_homogeneous False """ return f.rep.is_homogeneous
@property
[docs] def is_irreducible(f): """ Returns ``True`` if ``f`` has no factors over its domain. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(x**2 + x + 1, x, modulus=2).is_irreducible True >>> Poly(x**2 + 1, x, modulus=2).is_irreducible False """ return f.rep.is_irreducible
@property
[docs] def is_univariate(f): """ Returns ``True`` if ``f`` is a univariate polynomial. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x, y >>> Poly(x**2 + x + 1, x).is_univariate True >>> Poly(x*y**2 + x*y + 1, x, y).is_univariate False >>> Poly(x*y**2 + x*y + 1, x).is_univariate True >>> Poly(x**2 + x + 1, x, y).is_univariate False """ return len(f.gens) == 1
@property
[docs] def is_multivariate(f): """ Returns ``True`` if ``f`` is a multivariate polynomial. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x, y >>> Poly(x**2 + x + 1, x).is_multivariate False >>> Poly(x*y**2 + x*y + 1, x, y).is_multivariate True >>> Poly(x*y**2 + x*y + 1, x).is_multivariate False >>> Poly(x**2 + x + 1, x, y).is_multivariate True """ return len(f.gens) != 1
@property
[docs] def is_cyclotomic(f): """ Returns ``True`` if ``f`` is a cyclotomic polnomial. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> f = x**16 + x**14 - x**10 + x**8 - x**6 + x**2 + 1 >>> Poly(f).is_cyclotomic False >>> g = x**16 + x**14 - x**10 - x**8 - x**6 + x**2 + 1 >>> Poly(g).is_cyclotomic True """ return f.rep.is_cyclotomic
def __abs__(f): return f.abs() def __neg__(f): return f.neg() @_sympifyit('g', NotImplemented) def __add__(f, g): if not g.is_Poly: try: g = f.__class__(g, *f.gens) except PolynomialError: return f.as_expr() + g return f.add(g) @_sympifyit('g', NotImplemented) def __radd__(f, g): if not g.is_Poly: try: g = f.__class__(g, *f.gens) except PolynomialError: return g + f.as_expr() return g.add(f) @_sympifyit('g', NotImplemented) def __sub__(f, g): if not g.is_Poly: try: g = f.__class__(g, *f.gens) except PolynomialError: return f.as_expr() - g return f.sub(g) @_sympifyit('g', NotImplemented) def __rsub__(f, g): if not g.is_Poly: try: g = f.__class__(g, *f.gens) except PolynomialError: return g - f.as_expr() return g.sub(f) @_sympifyit('g', NotImplemented) def __mul__(f, g): if not g.is_Poly: try: g = f.__class__(g, *f.gens) except PolynomialError: return f.as_expr()*g return f.mul(g) @_sympifyit('g', NotImplemented) def __rmul__(f, g): if not g.is_Poly: try: g = f.__class__(g, *f.gens) except PolynomialError: return g*f.as_expr() return g.mul(f) @_sympifyit('n', NotImplemented) def __pow__(f, n): if n.is_Integer and n >= 0: return f.pow(n) else: return f.as_expr()**n @_sympifyit('g', NotImplemented) def __divmod__(f, g): if not g.is_Poly: g = f.__class__(g, *f.gens) return f.div(g) @_sympifyit('g', NotImplemented) def __rdivmod__(f, g): if not g.is_Poly: g = f.__class__(g, *f.gens) return g.div(f) @_sympifyit('g', NotImplemented) def __mod__(f, g): if not g.is_Poly: g = f.__class__(g, *f.gens) return f.rem(g) @_sympifyit('g', NotImplemented) def __rmod__(f, g): if not g.is_Poly: g = f.__class__(g, *f.gens) return g.rem(f) @_sympifyit('g', NotImplemented) def __floordiv__(f, g): if not g.is_Poly: g = f.__class__(g, *f.gens) return f.quo(g) @_sympifyit('g', NotImplemented) def __rfloordiv__(f, g): if not g.is_Poly: g = f.__class__(g, *f.gens) return g.quo(f) @_sympifyit('g', NotImplemented) def __div__(f, g): return f.as_expr()/g.as_expr() @_sympifyit('g', NotImplemented) def __rdiv__(f, g): return g.as_expr()/f.as_expr() __truediv__ = __div__ __rtruediv__ = __rdiv__ @_sympifyit('g', NotImplemented) def __eq__(f, g): if not g.is_Poly: try: g = f.__class__(g, f.gens, domain=f.get_domain()) except (PolynomialError, DomainError, CoercionFailed): return False if f.gens != g.gens: return False if f.rep.dom != g.rep.dom: try: dom = f.rep.dom.unify(g.rep.dom, f.gens) except UnificationFailed: return False f = f.set_domain(dom) g = g.set_domain(dom) return f.rep == g.rep @_sympifyit('g', NotImplemented) def __ne__(f, g): return not f.__eq__(g) def __bool__(f): return not f.is_zero def eq(f, g, strict=False): if not strict: return f.__eq__(g) else: return f._strict_eq(sympify(g)) def ne(f, g, strict=False): return not f.eq(g, strict=strict) def _strict_eq(f, g): return isinstance(g, f.__class__) and f.gens == g.gens and f.rep.eq(g.rep, strict=True)
[docs]class PurePoly(Poly): """Class for representing pure polynomials. """ def _hashable_content(self): """Allow SymPy to hash Poly instances. """ return (self.rep,) def __hash__(self): return super(PurePoly, self).__hash__() @property
[docs] def free_symbols(self): """ Free symbols of a polynomial. Examples ======== >>> from sympy import PurePoly >>> from sympy.abc import x, y >>> PurePoly(x**2 + 1).free_symbols set() >>> PurePoly(x**2 + y).free_symbols set() >>> PurePoly(x**2 + y, x).free_symbols set([y]) """ return self.free_symbols_in_domain
@_sympifyit('g', NotImplemented) def __eq__(f, g): if not g.is_Poly: try: g = f.__class__(g, f.gens, domain=f.get_domain()) except (PolynomialError, DomainError, CoercionFailed): return False if len(f.gens) != len(g.gens): return False if f.rep.dom != g.rep.dom: try: dom = f.rep.dom.unify(g.rep.dom, f.gens) except UnificationFailed: return False f = f.set_domain(dom) g = g.set_domain(dom) return f.rep == g.rep def _strict_eq(f, g): return isinstance(g, f.__class__) and f.rep.eq(g.rep, strict=True) def _unify(f, g): g = sympify(g) if not g.is_Poly: try: return f.rep.dom, f.per, f.rep, f.rep.per(f.rep.dom.from_sympy(g)) except CoercionFailed: raise UnificationFailed("can't unify %s with %s" % (f, g)) if len(f.gens) != len(g.gens): raise UnificationFailed("can't unify %s with %s" % (f, g)) if not (isinstance(f.rep, DMP) and isinstance(g.rep, DMP)): raise UnificationFailed("can't unify %s with %s" % (f, g)) cls = f.__class__ gens = f.gens dom = f.rep.dom.unify(g.rep.dom, gens) F = f.rep.convert(dom) G = g.rep.convert(dom) def per(rep, dom=dom, gens=gens, remove=None): if remove is not None: gens = gens[:remove]+gens[remove+1:] if not gens: return dom.to_sympy(rep) return cls.new(rep, *gens) return dom, per, F, G
[docs]def poly_from_expr(expr, *gens, **args): """Construct a polynomial from an expression. """ opt = options.build_options(gens, args) return _poly_from_expr(expr, opt)
def _poly_from_expr(expr, opt): """Construct a polynomial from an expression. """ orig, expr = expr, sympify(expr) if not isinstance(expr, Basic): raise PolificationFailed(opt, orig, expr) elif expr.is_Poly: poly = expr.__class__._from_poly(expr, opt) opt['gens'] = poly.gens opt['domain'] = poly.domain if opt.polys is None: opt['polys'] = True return poly, opt elif opt.expand: expr = expr.expand() try: rep, opt = _dict_from_expr(expr, opt) except GeneratorsNeeded: raise PolificationFailed(opt, orig, expr) monoms, coeffs = list(zip(*list(rep.items()))) domain = opt.domain if domain is None: domain, coeffs = construct_domain(coeffs, opt=opt) else: coeffs = list(map(domain.from_sympy, coeffs)) level = len(opt.gens)-1 poly = Poly.new(DMP.from_monoms_coeffs(monoms, coeffs, level, domain), *opt.gens) opt['domain'] = domain if opt.polys is None: opt['polys'] = False return poly, opt
[docs]def parallel_poly_from_expr(exprs, *gens, **args): """Construct polynomials from expressions. """ opt = options.build_options(gens, args) return _parallel_poly_from_expr(exprs, opt)
def _parallel_poly_from_expr(exprs, opt): """Construct polynomials from expressions. """ if len(exprs) == 2: f, g = exprs if isinstance(f, Poly) and isinstance(g, Poly): f = f.__class__._from_poly(f, opt) g = g.__class__._from_poly(g, opt) f, g = f.unify(g) opt['gens'] = f.gens opt['domain'] = f.domain if opt.polys is None: opt['polys'] = True return [f, g], opt origs, exprs = list(exprs), [] _exprs, _polys = [], [] failed = False for i, expr in enumerate(origs): expr = sympify(expr) if isinstance(expr, Basic): if expr.is_Poly: _polys.append(i) else: _exprs.append(i) if opt.expand: expr = expr.expand() else: failed = True exprs.append(expr) if failed: raise PolificationFailed(opt, origs, exprs, True) if _polys: # XXX: this is a temporary solution for i in _polys: exprs[i] = exprs[i].as_expr() try: reps, opt = _parallel_dict_from_expr(exprs, opt) except GeneratorsNeeded: raise PolificationFailed(opt, origs, exprs, True) coeffs_list, lengths = [], [] all_monoms = [] all_coeffs = [] for rep in reps: monoms, coeffs = list(zip(*list(rep.items()))) coeffs_list.extend(coeffs) all_monoms.append(monoms) lengths.append(len(coeffs)) domain = opt.domain if domain is None: domain, coeffs_list = construct_domain(coeffs_list, opt=opt) else: coeffs_list = list(map(domain.from_sympy, coeffs_list)) for k in lengths: all_coeffs.append(coeffs_list[:k]) coeffs_list = coeffs_list[k:] polys, level = [], len(opt.gens)-1 for monoms, coeffs in zip(all_monoms, all_coeffs): rep = DMP.from_monoms_coeffs(monoms, coeffs, level, domain) polys.append(Poly.new(rep, *opt.gens)) opt['domain'] = domain if opt.polys is None: opt['polys'] = bool(_polys) return polys, opt def _update_args(args, key, value): """Add a new ``(key, value)`` pair to arguments ``dict``. """ args = dict(args) if key not in args: args[key] = value return args
[docs]def degree(f, *gens, **args): """ Return the degree of ``f`` in the given variable. Examples ======== >>> from sympy import degree >>> from sympy.abc import x, y >>> degree(x**2 + y*x + 1, gen=x) 2 >>> degree(x**2 + y*x + 1, gen=y) 1 """ options.allowed_flags(args, ['gen', 'polys']) try: F, opt = poly_from_expr(f, *gens, **args) except PolificationFailed as exc: raise ComputationFailed('degree', 1, exc) return Integer(F.degree(opt.gen))
[docs]def degree_list(f, *gens, **args): """ Return a list of degrees of ``f`` in all variables. Examples ======== >>> from sympy import degree_list >>> from sympy.abc import x, y >>> degree_list(x**2 + y*x + 1) (2, 1) """ options.allowed_flags(args, ['polys']) try: F, opt = poly_from_expr(f, *gens, **args) except PolificationFailed as exc: raise ComputationFailed('degree_list', 1, exc) degrees = F.degree_list() return tuple(map(Integer, degrees))
[docs]def LC(f, *gens, **args): """ Return the leading coefficient of ``f``. Examples ======== >>> from sympy import LC >>> from sympy.abc import x, y >>> LC(4*x**2 + 2*x*y**2 + x*y + 3*y) 4 """ options.allowed_flags(args, ['polys']) try: F, opt = poly_from_expr(f, *gens, **args) except PolificationFailed as exc: raise ComputationFailed('LC', 1, exc) return F.LC(order=opt.order)
[docs]def LM(f, *gens, **args): """ Return the leading monomial of ``f``. Examples ======== >>> from sympy import LM >>> from sympy.abc import x, y >>> LM(4*x**2 + 2*x*y**2 + x*y + 3*y) x**2 """ options.allowed_flags(args, ['polys']) try: F, opt = poly_from_expr(f, *gens, **args) except PolificationFailed as exc: raise ComputationFailed('LM', 1, exc) monom = F.LM(order=opt.order) return monom.as_expr()
[docs]def LT(f, *gens, **args): """ Return the leading term of ``f``. Examples ======== >>> from sympy import LT >>> from sympy.abc import x, y >>> LT(4*x**2 + 2*x*y**2 + x*y + 3*y) 4*x**2 """ options.allowed_flags(args, ['polys']) try: F, opt = poly_from_expr(f, *gens, **args) except PolificationFailed as exc: raise ComputationFailed('LT', 1, exc) monom, coeff = F.LT(order=opt.order) return coeff*monom.as_expr()
[docs]def pdiv(f, g, *gens, **args): """ Compute polynomial pseudo-division of ``f`` and ``g``. Examples ======== >>> from sympy import pdiv >>> from sympy.abc import x >>> pdiv(x**2 + 1, 2*x - 4) (2*x + 4, 20) """ options.allowed_flags(args, ['polys']) try: (F, G), opt = parallel_poly_from_expr((f, g), *gens, **args) except PolificationFailed as exc: raise ComputationFailed('pdiv', 2, exc) q, r = F.pdiv(G) if not opt.polys: return q.as_expr(), r.as_expr() else: return q, r
[docs]def prem(f, g, *gens, **args): """ Compute polynomial pseudo-remainder of ``f`` and ``g``. Examples ======== >>> from sympy import prem >>> from sympy.abc import x >>> prem(x**2 + 1, 2*x - 4) 20 """ options.allowed_flags(args, ['polys']) try: (F, G), opt = parallel_poly_from_expr((f, g), *gens, **args) except PolificationFailed as exc: raise ComputationFailed('prem', 2, exc) r = F.prem(G) if not opt.polys: return r.as_expr() else: return r
[docs]def pquo(f, g, *gens, **args): """ Compute polynomial pseudo-quotient of ``f`` and ``g``. Examples ======== >>> from sympy import pquo >>> from sympy.abc import x >>> pquo(x**2 + 1, 2*x - 4) 2*x + 4 >>> pquo(x**2 - 1, 2*x - 1) 2*x + 1 """ options.allowed_flags(args, ['polys']) try: (F, G), opt = parallel_poly_from_expr((f, g), *gens, **args) except PolificationFailed as exc: raise ComputationFailed('pquo', 2, exc) q = F.pquo(G) if not opt.polys: return q.as_expr() else: return q
[docs]def pexquo(f, g, *gens, **args): """ Compute polynomial exact pseudo-quotient of ``f`` and ``g``. Examples ======== >>> from sympy import pexquo >>> from sympy.abc import x >>> pexquo(x**2 - 1, 2*x - 2) 2*x + 2 >>> pexquo(x**2 + 1, 2*x - 4) Traceback (most recent call last): ... ExactQuotientFailed: 2*x - 4 does not divide x**2 + 1 """ options.allowed_flags(args, ['polys']) try: (F, G), opt = parallel_poly_from_expr((f, g), *gens, **args) except PolificationFailed as exc: raise ComputationFailed('pexquo', 2, exc) q = F.pexquo(G) if not opt.polys: return q.as_expr() else: return q
[docs]def div(f, g, *gens, **args): """ Compute polynomial division of ``f`` and ``g``. Examples ======== >>> from sympy import div, ZZ, QQ >>> from sympy.abc import x >>> div(x**2 + 1, 2*x - 4, domain=ZZ) (0, x**2 + 1) >>> div(x**2 + 1, 2*x - 4, domain=QQ) (x/2 + 1, 5) """ options.allowed_flags(args, ['auto', 'polys']) try: (F, G), opt = parallel_poly_from_expr((f, g), *gens, **args) except PolificationFailed as exc: raise ComputationFailed('div', 2, exc) q, r = F.div(G, auto=opt.auto) if not opt.polys: return q.as_expr(), r.as_expr() else: return q, r
[docs]def rem(f, g, *gens, **args): """ Compute polynomial remainder of ``f`` and ``g``. Examples ======== >>> from sympy import rem, ZZ, QQ >>> from sympy.abc import x >>> rem(x**2 + 1, 2*x - 4, domain=ZZ) x**2 + 1 >>> rem(x**2 + 1, 2*x - 4, domain=QQ) 5 """ options.allowed_flags(args, ['auto', 'polys']) try: (F, G), opt = parallel_poly_from_expr((f, g), *gens, **args) except PolificationFailed as exc: raise ComputationFailed('rem', 2, exc) r = F.rem(G, auto=opt.auto) if not opt.polys: return r.as_expr() else: return r
[docs]def quo(f, g, *gens, **args): """ Compute polynomial quotient of ``f`` and ``g``. Examples ======== >>> from sympy import quo >>> from sympy.abc import x >>> quo(x**2 + 1, 2*x - 4) x/2 + 1 >>> quo(x**2 - 1, x - 1) x + 1 """ options.allowed_flags(args, ['auto', 'polys']) try: (F, G), opt = parallel_poly_from_expr((f, g), *gens, **args) except PolificationFailed as exc: raise ComputationFailed('quo', 2, exc) q = F.quo(G, auto=opt.auto) if not opt.polys: return q.as_expr() else: return q
[docs]def exquo(f, g, *gens, **args): """ Compute polynomial exact quotient of ``f`` and ``g``. Examples ======== >>> from sympy import exquo >>> from sympy.abc import x >>> exquo(x**2 - 1, x - 1) x + 1 >>> exquo(x**2 + 1, 2*x - 4) Traceback (most recent call last): ... ExactQuotientFailed: 2*x - 4 does not divide x**2 + 1 """ options.allowed_flags(args, ['auto', 'polys']) try: (F, G), opt = parallel_poly_from_expr((f, g), *gens, **args) except PolificationFailed as exc: raise ComputationFailed('exquo', 2, exc) q = F.exquo(G, auto=opt.auto) if not opt.polys: return q.as_expr() else: return q
[docs]def half_gcdex(f, g, *gens, **args): """ Half extended Euclidean algorithm of ``f`` and ``g``. Returns ``(s, h)`` such that ``h = gcd(f, g)`` and ``s*f = h (mod g)``. Examples ======== >>> from sympy import half_gcdex >>> from sympy.abc import x >>> half_gcdex(x**4 - 2*x**3 - 6*x**2 + 12*x + 15, x**3 + x**2 - 4*x - 4) (-x/5 + 3/5, x + 1) """ options.allowed_flags(args, ['auto', 'polys']) try: (F, G), opt = parallel_poly_from_expr((f, g), *gens, **args) except PolificationFailed as exc: f, g = exc.exprs if hasattr(f, 'half_gcdex'): try: return f.half_gcdex(g) except (SympifyError, ValueError): pass raise ComputationFailed('half_gcdex', 2, exc) s, h = F.half_gcdex(G, auto=opt.auto) if not opt.polys: return s.as_expr(), h.as_expr() else: return s, h
[docs]def gcdex(f, g, *gens, **args): """ Extended Euclidean algorithm of ``f`` and ``g``. Returns ``(s, t, h)`` such that ``h = gcd(f, g)`` and ``s*f + t*g = h``. Examples ======== >>> from sympy import gcdex >>> from sympy.abc import x >>> gcdex(x**4 - 2*x**3 - 6*x**2 + 12*x + 15, x**3 + x**2 - 4*x - 4) (-x/5 + 3/5, x**2/5 - 6*x/5 + 2, x + 1) """ options.allowed_flags(args, ['auto', 'polys']) try: (F, G), opt = parallel_poly_from_expr((f, g), *gens, **args) except PolificationFailed as exc: f, g = exc.exprs if hasattr(f, 'gcdex'): try: return f.gcdex(g) except (SympifyError, ValueError): pass raise ComputationFailed('gcdex', 2, exc) s, t, h = F.gcdex(G, auto=opt.auto) if not opt.polys: return s.as_expr(), t.as_expr(), h.as_expr() else: return s, t, h
[docs]def invert(f, g, *gens, **args): """ Invert ``f`` modulo ``g`` when possible. Examples ======== >>> from sympy import invert >>> from sympy.abc import x >>> invert(x**2 - 1, 2*x - 1) -4/3 >>> invert(x**2 - 1, x - 1) Traceback (most recent call last): ... NotInvertible: zero divisor """ options.allowed_flags(args, ['auto', 'polys']) try: (F, G), opt = parallel_poly_from_expr((f, g), *gens, **args) except PolificationFailed as exc: f, g = exc.exprs if hasattr(f, 'invert'): try: return f.invert(g) except (SympifyError, ValueError): pass raise ComputationFailed('invert', 2, exc) h = F.invert(G, auto=opt.auto) if not opt.polys: return h.as_expr() else: return h
[docs]def subresultants(f, g, *gens, **args): """ Compute subresultant PRS of ``f`` and ``g``. Examples ======== >>> from sympy import subresultants >>> from sympy.abc import x >>> subresultants(x**2 + 1, x**2 - 1) [x**2 + 1, x**2 - 1, -2] """ options.allowed_flags(args, ['polys']) try: (F, G), opt = parallel_poly_from_expr((f, g), *gens, **args) except PolificationFailed as exc: raise ComputationFailed('subresultants', 2, exc) result = F.subresultants(G) if not opt.polys: return [ r.as_expr() for r in result ] else: return result
[docs]def resultant(f, g, *gens, **args): """ Compute resultant of ``f`` and ``g``. Examples ======== >>> from sympy import resultant >>> from sympy.abc import x >>> resultant(x**2 + 1, x**2 - 1) 4 """ options.allowed_flags(args, ['polys']) try: (F, G), opt = parallel_poly_from_expr((f, g), *gens, **args) except PolificationFailed as exc: raise ComputationFailed('resultant', 2, exc) result = F.resultant(G) if not opt.polys: return result.as_expr() else: return result
[docs]def discriminant(f, *gens, **args): """ Compute discriminant of ``f``. Examples ======== >>> from sympy import discriminant >>> from sympy.abc import x >>> discriminant(x**2 + 2*x + 3) -8 """ options.allowed_flags(args, ['polys']) try: F, opt = poly_from_expr(f, *gens, **args) except PolificationFailed as exc: raise ComputationFailed('discriminant', 1, exc) result = F.discriminant() if not opt.polys: return result.as_expr() else: return result
[docs]def cofactors(f, g, *gens, **args): """ Compute GCD and cofactors of ``f`` and ``g``. Returns polynomials ``(h, cff, cfg)`` such that ``h = gcd(f, g)``, and ``cff = quo(f, h)`` and ``cfg = quo(g, h)`` are, so called, cofactors of ``f`` and ``g``. Examples ======== >>> from sympy import cofactors >>> from sympy.abc import x >>> cofactors(x**2 - 1, x**2 - 3*x + 2) (x - 1, x + 1, x - 2) """ options.allowed_flags(args, ['polys']) try: (F, G), opt = parallel_poly_from_expr((f, g), *gens, **args) except PolificationFailed as exc: f, g = exc.exprs if hasattr(f, 'cofactors'): try: return f.cofactors(g) except (SympifyError, ValueError): pass raise ComputationFailed('cofactors', 2, exc) h, cff, cfg = F.cofactors(G) if not opt.polys: return h.as_expr(), cff.as_expr(), cfg.as_expr() else: return h, cff, cfg
[docs]def gcd_list(seq, *gens, **args): """ Compute GCD of a list of polynomials. Examples ======== >>> from sympy import gcd_list >>> from sympy.abc import x >>> gcd_list([x**3 - 1, x**2 - 1, x**2 - 3*x + 2]) x - 1 """ if not gens and not args: if not seq: return S.Zero seq = sympify(seq) if all(s.is_Number for s in seq): result, numbers = seq[0], seq[1:] for number in numbers: result = result.gcd(number) if result is S.One: break return result options.allowed_flags(args, ['polys']) try: polys, opt = parallel_poly_from_expr(seq, *gens, **args) except PolificationFailed as exc: raise ComputationFailed('gcd_list', len(seq), exc) if not polys: if not opt.polys: return S.Zero else: return Poly(0, opt=opt) result, polys = polys[0], polys[1:] for poly in polys: result = result.gcd(poly) if result.is_one: break if not opt.polys: return result.as_expr() else: return result
[docs]def gcd(f, g=None, *gens, **args): """ Compute GCD of ``f`` and ``g``. Examples ======== >>> from sympy import gcd >>> from sympy.abc import x >>> gcd(x**2 - 1, x**2 - 3*x + 2) x - 1 """ if hasattr(f, '__iter__'): if g is not None: gens = (g,) + gens return gcd_list(f, *gens, **args) options.allowed_flags(args, ['polys']) try: (F, G), opt = parallel_poly_from_expr((f, g), *gens, **args) except PolificationFailed as exc: f, g = exc.exprs if hasattr(f, 'gcd'): try: if f.is_Float: f = Rational(str(f)) if g.is_Float: g = Rational(str(g)) return f.gcd(g) except (SympifyError, ValueError): pass raise ComputationFailed('gcd', 2, exc) result = F.gcd(G) if not opt.polys: return result.as_expr() else: return result
[docs]def lcm_list(seq, *gens, **args): """ Compute LCM of a list of polynomials. Examples ======== >>> from sympy import lcm_list >>> from sympy.abc import x >>> lcm_list([x**3 - 1, x**2 - 1, x**2 - 3*x + 2]) x**5 - x**4 - 2*x**3 - x**2 + x + 2 """ if not gens and not args: if not seq: return S.One seq = sympify(seq) if all(s.is_Number for s in seq): result, numbers = seq[0], seq[1:] for number in numbers: result = result.lcm(number) return result options.allowed_flags(args, ['polys']) try: polys, opt = parallel_poly_from_expr(seq, *gens, **args) except PolificationFailed as exc: raise ComputationFailed('lcm_list', len(seq), exc) if not polys: if not opt.polys: return S.One else: return Poly(1, opt=opt) result, polys = polys[0], polys[1:] for poly in polys: result = result.lcm(poly) if not opt.polys: return result.as_expr() else: return result
[docs]def lcm(f, g=None, *gens, **args): """ Compute LCM of ``f`` and ``g``. Examples ======== >>> from sympy import lcm >>> from sympy.abc import x >>> lcm(x**2 - 1, x**2 - 3*x + 2) x**3 - 2*x**2 - x + 2 """ if hasattr(f, '__iter__'): if g is not None: gens = (g,) + gens return lcm_list(f, *gens, **args) options.allowed_flags(args, ['polys']) try: (F, G), opt = parallel_poly_from_expr((f, g), *gens, **args) except PolificationFailed as exc: f, g = exc.exprs if hasattr(f, 'lcm'): try: return f.lcm(g) except (SympifyError, ValueError): pass raise ComputationFailed('lcm', 2, exc) result = F.lcm(G) if not opt.polys: return result.as_expr() else: return result
[docs]def terms_gcd(f, *gens, **args): """ Remove GCD of terms from ``f``. If the ``deep`` flag is True, then the arguments of ``f`` will have terms_gcd applied to them. If a fraction is factored out of ``f`` and ``f`` is an Add, then an unevaluated Mul will be returned so that automatic simplification does not redistribute it. The hint ``clear``, when set to False, can be used to prevent such factoring when all coefficients are not fractions. Examples ======== >>> from sympy import terms_gcd, cos, pi >>> from sympy.abc import x, y >>> terms_gcd(x**6*y**2 + x**3*y, x, y) x**3*y*(x**3*y + 1) The default action of polys routines is to expand the expression given to them. terms_gcd follows this behavior: >>> terms_gcd((3+3*x)*(x+x*y)) 3*x*(x*y + x + y + 1) If this is not desired then the hint ``expand`` can be set to False. In this case the expression will be treated as though it were comprised of one or more terms: >>> terms_gcd((3+3*x)*(x+x*y), expand=False) (3*x + 3)*(x*y + x) In order to traverse factors of a Mul or the arguments of other functions, the ``deep`` hint can be used: >>> terms_gcd((3 + 3*x)*(x + x*y), expand=False, deep=True) 3*x*(x + 1)*(y + 1) >>> terms_gcd(cos(x + x*y), deep=True) cos(x*(y + 1)) Rationals are factored out by default: >>> terms_gcd(x + y/2) (2*x + y)/2 Only the y-term had a coefficient that was a fraction; if one does not want to factor out the 1/2 in cases like this, the flag ``clear`` can be set to False: >>> terms_gcd(x + y/2, clear=False) x + y/2 The ``clear`` flag is ignored if all coefficients are fractions: >>> terms_gcd(x/3 + y/2, clear=False) (2*x + 3*y)/6 See Also ======== sympy.core.exprtools.gcd_terms, sympy.core.exprtools.factor_terms """ if not isinstance(f, Expr) or f.is_Atom: return sympify(f) if args.get('deep', False): new = f.func(*[terms_gcd(a, *gens, **args) for a in f.args]) args.pop('deep') args['expand'] = False return terms_gcd(new, *gens, **args) clear = args.pop('clear', True) options.allowed_flags(args, ['polys']) try: F, opt = poly_from_expr(f, *gens, **args) except PolificationFailed as exc: return exc.expr J, f = F.terms_gcd() if opt.domain.has_Ring: if opt.domain.has_Field: denom, f = f.clear_denoms(convert=True) coeff, f = f.primitive() if opt.domain.has_Field: coeff /= denom else: coeff = S.One term = Mul(*[ x**j for x, j in zip(f.gens, J) ]) return _keep_coeff(coeff, term*f.as_expr(), clear=clear)
[docs]def trunc(f, p, *gens, **args): """ Reduce ``f`` modulo a constant ``p``. Examples ======== >>> from sympy import trunc >>> from sympy.abc import x >>> trunc(2*x**3 + 3*x**2 + 5*x + 7, 3) -x**3 - x + 1 """ options.allowed_flags(args, ['auto', 'polys']) try: F, opt = poly_from_expr(f, *gens, **args) except PolificationFailed as exc: raise ComputationFailed('trunc', 1, exc) result = F.trunc(sympify(p)) if not opt.polys: return result.as_expr() else: return result
[docs]def monic(f, *gens, **args): """ Divide all coefficients of ``f`` by ``LC(f)``. Examples ======== >>> from sympy import monic >>> from sympy.abc import x >>> monic(3*x**2 + 4*x + 2) x**2 + 4*x/3 + 2/3 """ options.allowed_flags(args, ['auto', 'polys']) try: F, opt = poly_from_expr(f, *gens, **args) except PolificationFailed as exc: raise ComputationFailed('monic', 1, exc) result = F.monic(auto=opt.auto) if not opt.polys: return result.as_expr() else: return result
[docs]def content(f, *gens, **args): """ Compute GCD of coefficients of ``f``. Examples ======== >>> from sympy import content >>> from sympy.abc import x >>> content(6*x**2 + 8*x + 12) 2 """ options.allowed_flags(args, ['polys']) try: F, opt = poly_from_expr(f, *gens, **args) except PolificationFailed as exc: raise ComputationFailed('content', 1, exc) return F.content()
[docs]def primitive(f, *gens, **args): """ Compute content and the primitive form of ``f``. Examples ======== >>> from sympy.polys.polytools import primitive >>> from sympy.abc import x, y >>> primitive(6*x**2 + 8*x + 12) (2, 3*x**2 + 4*x + 6) >>> eq = (2 + 2*x)*x + 2 Expansion is performed by default: >>> primitive(eq) (2, x**2 + x + 1) Set ``expand`` to False to shut this off. Note that the extraction will not be recursive; use the as_content_primitive method for recursive, non-destructive Rational extraction. >>> primitive(eq, expand=False) (1, x*(2*x + 2) + 2) >>> eq.as_content_primitive() (2, x*(x + 1) + 1) """ options.allowed_flags(args, ['polys']) try: F, opt = poly_from_expr(f, *gens, **args) except PolificationFailed as exc: raise ComputationFailed('primitive', 1, exc) cont, result = F.primitive() if not opt.polys: return cont, result.as_expr() else: return cont, result
[docs]def compose(f, g, *gens, **args): """ Compute functional composition ``f(g)``. Examples ======== >>> from sympy import compose >>> from sympy.abc import x >>> compose(x**2 + x, x - 1) x**2 - x """ options.allowed_flags(args, ['polys']) try: (F, G), opt = parallel_poly_from_expr((f, g), *gens, **args) except PolificationFailed as exc: raise ComputationFailed('compose', 2, exc) result = F.compose(G) if not opt.polys: return result.as_expr() else: return result
[docs]def decompose(f, *gens, **args): """ Compute functional decomposition of ``f``. Examples ======== >>> from sympy import decompose >>> from sympy.abc import x >>> decompose(x**4 + 2*x**3 - x - 1) [x**2 - x - 1, x**2 + x] """ options.allowed_flags(args, ['polys']) try: F, opt = poly_from_expr(f, *gens, **args) except PolificationFailed as exc: raise ComputationFailed('decompose', 1, exc) result = F.decompose() if not opt.polys: return [ r.as_expr() for r in result ] else: return result
[docs]def sturm(f, *gens, **args): """ Compute Sturm sequence of ``f``. Examples ======== >>> from sympy import sturm >>> from sympy.abc import x >>> sturm(x**3 - 2*x**2 + x - 3) [x**3 - 2*x**2 + x - 3, 3*x**2 - 4*x + 1, 2*x/9 + 25/9, -2079/4] """ options.allowed_flags(args, ['auto', 'polys']) try: F, opt = poly_from_expr(f, *gens, **args) except PolificationFailed as exc: raise ComputationFailed('sturm', 1, exc) result = F.sturm(auto=opt.auto) if not opt.polys: return [ r.as_expr() for r in result ] else: return result
[docs]def gff_list(f, *gens, **args): """ Compute a list of greatest factorial factors of ``f``. Examples ======== >>> from sympy import gff_list, ff >>> from sympy.abc import x >>> f = x**5 + 2*x**4 - x**3 - 2*x**2 >>> gff_list(f) [(x, 1), (x + 2, 4)] >>> (ff(x, 1)*ff(x + 2, 4)).expand() == f True """ options.allowed_flags(args, ['polys']) try: F, opt = poly_from_expr(f, *gens, **args) except PolificationFailed as exc: raise ComputationFailed('gff_list', 1, exc) factors = F.gff_list() if not opt.polys: return [ (g.as_expr(), k) for g, k in factors ] else: return factors
[docs]def gff(f, *gens, **args): """Compute greatest factorial factorization of ``f``. """ raise NotImplementedError('symbolic falling factorial')
[docs]def sqf_norm(f, *gens, **args): """ Compute square-free norm of ``f``. Returns ``s``, ``f``, ``r``, such that ``g(x) = f(x-sa)`` and ``r(x) = Norm(g(x))`` is a square-free polynomial over ``K``, where ``a`` is the algebraic extension of the ground domain. Examples ======== >>> from sympy import sqf_norm, sqrt >>> from sympy.abc import x >>> sqf_norm(x**2 + 1, extension=[sqrt(3)]) (1, x**2 - 2*sqrt(3)*x + 4, x**4 - 4*x**2 + 16) """ options.allowed_flags(args, ['polys']) try: F, opt = poly_from_expr(f, *gens, **args) except PolificationFailed as exc: raise ComputationFailed('sqf_norm', 1, exc) s, g, r = F.sqf_norm() if not opt.polys: return Integer(s), g.as_expr(), r.as_expr() else: return Integer(s), g, r
[docs]def sqf_part(f, *gens, **args): """ Compute square-free part of ``f``. Examples ======== >>> from sympy import sqf_part >>> from sympy.abc import x >>> sqf_part(x**3 - 3*x - 2) x**2 - x - 2 """ options.allowed_flags(args, ['polys']) try: F, opt = poly_from_expr(f, *gens, **args) except PolificationFailed as exc: raise ComputationFailed('sqf_part', 1, exc) result = F.sqf_part() if not opt.polys: return result.as_expr() else: return result
def _sorted_factors(factors, method): """Sort a list of ``(expr, exp)`` pairs. """ if method == 'sqf': def key(obj): poly, exp = obj rep = poly.rep.rep return (exp, len(rep), rep) else: def key(obj): poly, exp = obj rep = poly.rep.rep return (len(rep), exp, rep) return sorted(factors, key=key) def _factors_product(factors): """Multiply a list of ``(expr, exp)`` pairs. """ return Mul(*[ f.as_expr()**k for f, k in factors ]) def _symbolic_factor_list(expr, opt, method): """Helper function for :func:`_symbolic_factor`. """ coeff, factors = S.One, [] for arg in Mul.make_args(expr): if arg.is_Number: coeff *= arg continue elif arg.is_Pow: base, exp = arg.args if base.is_Number: factors.append((base, exp)) continue else: base, exp = arg, S.One try: poly, _ = _poly_from_expr(base, opt) except PolificationFailed as exc: factors.append((exc.expr, exp)) else: func = getattr(poly, method + '_list') _coeff, _factors = func() if _coeff is not S.One: if exp.is_Integer: coeff *= _coeff**exp elif _coeff.is_positive: factors.append((_coeff, exp)) else: _factors.append((_coeff, None)) if exp is S.One: factors.extend(_factors) elif exp.is_integer or len(_factors) == 1: factors.extend([ (f, k*exp) for f, k in _factors ]) else: other = [] for f, k in _factors: if f.as_expr().is_positive: factors.append((f, k*exp)) elif k is not None: other.append((f, k)) else: other.append((f, S.One)) if len(other) == 1: f, k = other[0] factors.append((f, k*exp)) else: factors.append((_factors_product(other), exp)) return coeff, factors def _symbolic_factor(expr, opt, method): """Helper function for :func:`_factor`. """ if isinstance(expr, Expr) and not expr.is_Relational: coeff, factors = _symbolic_factor_list(together(expr), opt, method) return _keep_coeff(coeff, _factors_product(factors)) elif hasattr(expr, 'args'): return expr.func(*[ _symbolic_factor(arg, opt, method) for arg in expr.args ]) elif hasattr(expr, '__iter__'): return expr.__class__([ _symbolic_factor(arg, opt, method) for arg in expr ]) else: return expr def _generic_factor_list(expr, gens, args, method): """Helper function for :func:`sqf_list` and :func:`factor_list`. """ options.allowed_flags(args, ['frac', 'polys']) opt = options.build_options(gens, args) expr = sympify(expr) if isinstance(expr, Expr) and not expr.is_Relational: numer, denom = together(expr).as_numer_denom() cp, fp = _symbolic_factor_list(numer, opt, method) cq, fq = _symbolic_factor_list(denom, opt, method) if fq and not opt.frac: raise PolynomialError("a polynomial expected, got %s" % expr) _opt = opt.clone(dict(expand=True)) for factors in (fp, fq): for i, (f, k) in enumerate(factors): if not f.is_Poly: f, _ = _poly_from_expr(f, _opt) factors[i] = (f, k) fp = _sorted_factors(fp, method) fq = _sorted_factors(fq, method) if not opt.polys: fp = [ (f.as_expr(), k) for f, k in fp ] fq = [ (f.as_expr(), k) for f, k in fq ] coeff = cp/cq if not opt.frac: return coeff, fp else: return coeff, fp, fq else: raise PolynomialError("a polynomial expected, got %s" % expr) def _generic_factor(expr, gens, args, method): """Helper function for :func:`sqf` and :func:`factor`. """ options.allowed_flags(args, []) opt = options.build_options(gens, args) return _symbolic_factor(sympify(expr), opt, method)
[docs]def sqf_list(f, *gens, **args): """ Compute a list of square-free factors of ``f``. Examples ======== >>> from sympy import sqf_list >>> from sympy.abc import x >>> sqf_list(2*x**5 + 16*x**4 + 50*x**3 + 76*x**2 + 56*x + 16) (2, [(x + 1, 2), (x + 2, 3)]) """ return _generic_factor_list(f, gens, args, method='sqf')
[docs]def sqf(f, *gens, **args): """ Compute square-free factorization of ``f``. Examples ======== >>> from sympy import sqf >>> from sympy.abc import x >>> sqf(2*x**5 + 16*x**4 + 50*x**3 + 76*x**2 + 56*x + 16) 2*(x + 1)**2*(x + 2)**3 """ return _generic_factor(f, gens, args, method='sqf')
[docs]def factor_list(f, *gens, **args): """ Compute a list of irreducible factors of ``f``. Examples ======== >>> from sympy import factor_list >>> from sympy.abc import x, y >>> factor_list(2*x**5 + 2*x**4*y + 4*x**3 + 4*x**2*y + 2*x + 2*y) (2, [(x + y, 1), (x**2 + 1, 2)]) """ return _generic_factor_list(f, gens, args, method='factor')
[docs]def factor(f, *gens, **args): """ Compute the factorization of ``f`` into irreducibles. (Use factorint to factor an integer.) There two modes implemented: symbolic and formal. If ``f`` is not an instance of :class:`Poly` and generators are not specified, then the former mode is used. Otherwise, the formal mode is used. In symbolic mode, :func:`factor` will traverse the expression tree and factor its components without any prior expansion, unless an instance of :class:`Add` is encountered (in this case formal factorization is used). This way :func:`factor` can handle large or symbolic exponents. By default, the factorization is computed over the rationals. To factor over other domain, e.g. an algebraic or finite field, use appropriate options: ``extension``, ``modulus`` or ``domain``. Examples ======== >>> from sympy import factor, sqrt >>> from sympy.abc import x, y >>> factor(2*x**5 + 2*x**4*y + 4*x**3 + 4*x**2*y + 2*x + 2*y) 2*(x + y)*(x**2 + 1)**2 >>> factor(x**2 + 1) x**2 + 1 >>> factor(x**2 + 1, modulus=2) (x + 1)**2 >>> factor(x**2 + 1, gaussian=True) (x - I)*(x + I) >>> factor(x**2 - 2, extension=sqrt(2)) (x - sqrt(2))*(x + sqrt(2)) >>> factor((x**2 - 1)/(x**2 + 4*x + 4)) (x - 1)*(x + 1)/(x + 2)**2 >>> factor((x**2 + 4*x + 4)**10000000*(x**2 + 1)) (x + 2)**20000000*(x**2 + 1) """ try: return _generic_factor(f, gens, args, method='factor') except PolynomialError as msg: if not f.is_commutative: from sympy.core.exprtools import factor_nc return factor_nc(f) else: raise PolynomialError(msg)
[docs]def intervals(F, all=False, eps=None, inf=None, sup=None, strict=False, fast=False, sqf=False): """ Compute isolating intervals for roots of ``f``. Examples ======== >>> from sympy import intervals >>> from sympy.abc import x >>> intervals(x**2 - 3) [((-2, -1), 1), ((1, 2), 1)] >>> intervals(x**2 - 3, eps=1e-2) [((-26/15, -19/11), 1), ((19/11, 26/15), 1)] """ if not hasattr(F, '__iter__'): try: F = Poly(F) except GeneratorsNeeded: return [] return F.intervals(all=all, eps=eps, inf=inf, sup=sup, fast=fast, sqf=sqf) else: polys, opt = parallel_poly_from_expr(F, domain='QQ') if len(opt.gens) > 1: raise MultivariatePolynomialError for i, poly in enumerate(polys): polys[i] = poly.rep.rep if eps is not None: eps = opt.domain.convert(eps) if eps <= 0: raise ValueError("'eps' must be a positive rational") if inf is not None: inf = opt.domain.convert(inf) if sup is not None: sup = opt.domain.convert(sup) intervals = dup_isolate_real_roots_list(polys, opt.domain, eps=eps, inf=inf, sup=sup, strict=strict, fast=fast) result = [] for (s, t), indices in intervals: s, t = opt.domain.to_sympy(s), opt.domain.to_sympy(t) result.append(((s, t), indices)) return result
[docs]def refine_root(f, s, t, eps=None, steps=None, fast=False, check_sqf=False): """ Refine an isolating interval of a root to the given precision. Examples ======== >>> from sympy import refine_root >>> from sympy.abc import x >>> refine_root(x**2 - 3, 1, 2, eps=1e-2) (19/11, 26/15) """ try: F = Poly(f) except GeneratorsNeeded: raise PolynomialError("can't refine a root of %s, not a polynomial" % f) return F.refine_root(s, t, eps=eps, steps=steps, fast=fast, check_sqf=check_sqf)
[docs]def count_roots(f, inf=None, sup=None): """ Return the number of roots of ``f`` in ``[inf, sup]`` interval. If one of ``inf`` or ``sup`` is complex, it will return the number of roots in the complex rectangle with corners at ``inf`` and ``sup``. Examples ======== >>> from sympy import count_roots, I >>> from sympy.abc import x >>> count_roots(x**4 - 4, -3, 3) 2 >>> count_roots(x**4 - 4, 0, 1 + 3*I) 1 """ try: F = Poly(f, greedy=False) except GeneratorsNeeded: raise PolynomialError("can't count roots of %s, not a polynomial" % f) return F.count_roots(inf=inf, sup=sup)
[docs]def real_roots(f, multiple=True): """ Return a list of real roots with multiplicities of ``f``. Examples ======== >>> from sympy import real_roots >>> from sympy.abc import x >>> real_roots(2*x**3 - 7*x**2 + 4*x + 4) [-1/2, 2, 2] """ try: F = Poly(f, greedy=False) except GeneratorsNeeded: raise PolynomialError("can't compute real roots of %s, not a polynomial" % f) return F.real_roots(multiple=multiple)
[docs]def nroots(f, n=15, maxsteps=50, cleanup=True, error=False): """ Compute numerical approximations of roots of ``f``. Examples ======== >>> from sympy import nroots >>> from sympy.abc import x >>> nroots(x**2 - 3, n=15) [-1.73205080756888, 1.73205080756888] >>> nroots(x**2 - 3, n=30) [-1.73205080756887729352744634151, 1.73205080756887729352744634151] """ try: F = Poly(f, greedy=False) except GeneratorsNeeded: raise PolynomialError("can't compute numerical roots of %s, not a polynomial" % f) return F.nroots(n=n, maxsteps=maxsteps, cleanup=cleanup, error=error)
[docs]def ground_roots(f, *gens, **args): """ Compute roots of ``f`` by factorization in the ground domain. Examples ======== >>> from sympy import ground_roots >>> from sympy.abc import x >>> ground_roots(x**6 - 4*x**4 + 4*x**3 - x**2) {0: 2, 1: 2} """ options.allowed_flags(args, []) try: F, opt = poly_from_expr(f, *gens, **args) except PolificationFailed as exc: raise ComputationFailed('ground_roots', 1, exc) return F.ground_roots()
[docs]def nth_power_roots_poly(f, n, *gens, **args): """ Construct a polynomial with n-th powers of roots of ``f``. Examples ======== >>> from sympy import nth_power_roots_poly, factor, roots >>> from sympy.abc import x >>> f = x**4 - x**2 + 1 >>> g = factor(nth_power_roots_poly(f, 2)) >>> g (x**2 - x + 1)**2 >>> R_f = [ (r**2).expand() for r in roots(f) ] >>> R_g = list(roots(g).keys()) >>> set(R_f) == set(R_g) True """ options.allowed_flags(args, []) try: F, opt = poly_from_expr(f, *gens, **args) except PolificationFailed as exc: raise ComputationFailed('nth_power_roots_poly', 1, exc) result = F.nth_power_roots_poly(n) if not opt.polys: return result.as_expr() else: return result
[docs]def cancel(f, *gens, **args): """ Cancel common factors in a rational function ``f``. Examples ======== >>> from sympy import cancel >>> from sympy.abc import x >>> cancel((2*x**2 - 2)/(x**2 - 2*x + 1)) (2*x + 2)/(x - 1) """ options.allowed_flags(args, ['polys']) f = sympify(f) if not isinstance(f, (tuple, Tuple)): if f.is_Number: return f else: p, q = f.as_numer_denom() else: p, q = f try: (F, G), opt = parallel_poly_from_expr((p, q), *gens, **args) except PolificationFailed: if not isinstance(f, (tuple, Tuple)): return f else: return S.One, p, q c, P, Q = F.cancel(G) if not isinstance(f, (tuple, Tuple)): return c*(P.as_expr()/Q.as_expr()) else: if not opt.polys: return c, P.as_expr(), Q.as_expr() else: return c, P, Q
[docs]def reduced(f, G, *gens, **args): """ Reduces a polynomial ``f`` modulo a set of polynomials ``G``. Given a polynomial ``f`` and a set of polynomials ``G = (g_1, ..., g_n)``, computes a set of quotients ``q = (q_1, ..., q_n)`` and the remainder ``r`` such that ``f = q_1*f_1 + ... + q_n*f_n + r``, where ``r`` vanishes or ``r`` is a completely reduced polynomial with respect to ``G``. Examples ======== >>> from sympy import reduced >>> from sympy.abc import x, y >>> reduced(2*x**4 + y**2 - x**2 + y**3, [x**3 - x, y**3 - y]) ([2*x, 1], x**2 + y**2 + y) """ options.allowed_flags(args, ['polys', 'auto']) try: polys, opt = parallel_poly_from_expr([f] + list(G), *gens, **args) except PolificationFailed as exc: raise ComputationFailed('reduced', 0, exc) domain = opt.domain retract = False if opt.auto and domain.has_Ring and not domain.has_Field: opt = opt.clone(dict(domain = domain.get_field())) retract = True for i, poly in enumerate(polys): poly = poly.set_domain(opt.domain).rep.to_dict() polys[i] = sdp_from_dict(poly, opt.order) level = len(opt.gens)-1 Q, r = sdp_div(polys[0], polys[1:], level, opt.order, opt.domain) Q = [ Poly._from_dict(dict(q), opt) for q in Q ] r = Poly._from_dict(dict(r), opt) if retract: try: _Q, _r = [ q.to_ring() for q in Q ], r.to_ring() except CoercionFailed: pass else: Q, r = _Q, _r if not opt.polys: return [ q.as_expr() for q in Q ], r.as_expr() else: return Q, r
[docs]def groebner(F, *gens, **args): """ Computes the reduced Groebner basis for a set of polynomials. Use the ``order`` argument to set the monomial ordering that will be used to compute the basis. Allowed orders are ``lex``, ``grlex`` and ``grevlex``. If no order is specified, it defaults to ``lex``. Examples ======== >>> from sympy import groebner >>> from sympy.abc import x, y >>> F = [x*y - 2*y, 2*y**2 - x**2] >>> groebner(F, x, y, order='lex') GroebnerBasis([x**2 - 2*y**2, x*y - 2*y, y**3 - 2*y], x, y, domain='ZZ', order='lex') >>> groebner(F, x, y, order='grlex') GroebnerBasis([y**3 - 2*y, x**2 - 2*y**2, x*y - 2*y], x, y, domain='ZZ', order='grlex') >>> groebner(F, x, y, order='grevlex') GroebnerBasis([y**3 - 2*y, x**2 - 2*y**2, x*y - 2*y], x, y, domain='ZZ', order='grevlex') By default, an improved implementation of the Buchberger algorithm is used. Optionally, an implementation of the F5B algorithm can be used. The algorithm can be set using ``method`` flag or with the :func:`setup` function from :mod:`sympy.polys.polyconfig`: >>> F = [x**2 - x - 1, (2*x - 1) * y - (x**10 - (1 - x)**10)] >>> groebner(F, x, y, method='buchberger') GroebnerBasis([x**2 - x - 1, y - 55], x, y, domain='ZZ', order='lex') >>> groebner(F, x, y, method='f5b') GroebnerBasis([x**2 - x - 1, y - 55], x, y, domain='ZZ', order='lex') References ========== 1. [Buchberger01]_ 2. [Cox97]_ """ return GroebnerBasis(F, *gens, **args)
[docs]def is_zero_dimensional(F, *gens, **args): """ Checks if the ideal generated by a Groebner basis is zero-dimensional. The algorithm checks if the set of monomials not divisible by the leading monomial of any element of ``F`` is bounded. References ========== David A. Cox, John B. Little, Donal O'Shea. Ideals, Varieties and Algorithms, 3rd edition, p. 230 """ return GroebnerBasis(F, *gens, **args).is_zero_dimensional
[docs]class GroebnerBasis(Basic): """Represents a reduced Groebner basis. """ __slots__ = ['_basis', '_options'] def __new__(cls, F, *gens, **args): """Compute a reduced Groebner basis for a system of polynomials. """ options.allowed_flags(args, ['polys', 'method']) try: polys, opt = parallel_poly_from_expr(F, *gens, **args) except PolificationFailed as exc: raise ComputationFailed('groebner', len(F), exc) domain = opt.domain if domain.has_assoc_Field: opt.domain = domain.get_field() else: raise DomainError("can't compute a Groebner basis over %s" % opt.domain) for i, poly in enumerate(polys): poly = poly.set_domain(opt.domain).rep.to_dict() polys[i] = sdp_from_dict(poly, opt.order) level = len(opt.gens) - 1 G = sdp_groebner(polys, level, opt.order, opt.domain, method=opt.method) G = [ Poly._from_dict(dict(g), opt) for g in G ] if not domain.has_Field: G = [ g.clear_denoms(convert=True)[1] for g in G ] opt.domain = domain return cls._new(G, opt) @classmethod def _new(cls, basis, options): obj = Basic.__new__(cls) obj._basis = tuple(basis) obj._options = options return obj @property def args(self): return (Tuple(*self._basis), Tuple(*self._options.gens)) @property def exprs(self): return [ poly.as_expr() for poly in self._basis ] @property def polys(self): return list(self._basis) @property def gens(self): return self._options.gens @property def domain(self): return self._options.domain @property def order(self): return self._options.order def __len__(self): return len(self._basis) def __iter__(self): if self._options.polys: return iter(self.polys) else: return iter(self.exprs) def __getitem__(self, item): if self._options.polys: basis = self.polys else: basis = self.exprs return basis[item] def __hash__(self): return hash((self._basis, tuple(self._options.items()))) def __eq__(self, other): if isinstance(other, self.__class__): return self._basis == other._basis and self._options == other._options elif iterable(other): return self.polys == list(other) or self.exprs == list(other) else: return False def __ne__(self, other): return not self.__eq__(other) @property
[docs] def is_zero_dimensional(self): """ Checks if the ideal generated by a Groebner basis is zero-dimensional. The algorithm checks if the set of monomials not divisible by the leading monomial of any element of ``F`` is bounded. References ========== David A. Cox, John B. Little, Donal O'Shea. Ideals, Varieties and Algorithms, 3rd edition, p. 230 """ def single_var(monomial): return sum(map(bool, monomial)) == 1 exponents = Monomial([0]*len(self.gens)) order = self._options.order for poly in self.polys: monomial = poly.LM(order=order) if single_var(monomial): exponents *= monomial # If any element of the exponents vector is zero, then there's # a variable for which there's no degree bound and the ideal # generated by this Groebner basis isn't zero-dimensional. return all(exponents)
[docs] def fglm(self, order): """ Convert a Groebner basis from one ordering to another. The FGLM algorithm converts reduced Groebner bases of zero-dimensional ideals from one ordering to another. This method is often used when it is infeasible to compute a Groebner basis with respect to a particular ordering directly. Examples ======== >>> from sympy.abc import x, y >>> from sympy import groebner >>> F = [x**2 - 3*y - x + 1, y**2 - 2*x + y - 1] >>> G = groebner(F, x, y, order='grlex') >>> list(G.fglm('lex')) [2*x - y**2 - y + 1, y**4 + 2*y**3 - 3*y**2 - 16*y + 7] >>> list(groebner(F, x, y, order='lex')) [2*x - y**2 - y + 1, y**4 + 2*y**3 - 3*y**2 - 16*y + 7] References ========== J.C. Faugere, P. Gianni, D. Lazard, T. Mora (1994). Efficient Computation of Zero-dimensional Groebner Bases by Change of Ordering J.C. Faugere's lecture notes: http://www-salsa.lip6.fr/~jcf/Papers/2010_MPRI5e.pdf """ opt = self._options src_order = opt.order dst_order = monomial_key(order) if src_order == dst_order: return self if not self.is_zero_dimensional: raise NotImplementedError("can't convert Groebner bases of ideals with positive dimension") polys = list(self._basis) domain = opt.domain opt = opt.clone(dict( domain = domain.get_field(), order = dst_order, )) for i, poly in enumerate(polys): poly = poly.set_domain(opt.domain).rep.to_dict() polys[i] = sdp_from_dict(poly, src_order) level = len(opt.gens) - 1 G = matrix_fglm(polys, level, src_order, dst_order, opt.domain) G = [ Poly._from_dict(dict(g), opt) for g in G ] if not domain.has_Field: G = [ g.clear_denoms(convert=True)[1] for g in G ] opt.domain = domain return self._new(G, opt)
[docs] def reduce(self, expr, auto=True): """ Reduces a polynomial modulo a Groebner basis. Given a polynomial ``f`` and a set of polynomials ``G = (g_1, ..., g_n)``, computes a set of quotients ``q = (q_1, ..., q_n)`` and the remainder ``r`` such that ``f = q_1*f_1 + ... + q_n*f_n + r``, where ``r`` vanishes or ``r`` is a completely reduced polynomial with respect to ``G``. Examples ======== >>> from sympy import groebner, expand >>> from sympy.abc import x, y >>> f = 2*x**4 - x**2 + y**3 + y**2 >>> G = groebner([x**3 - x, y**3 - y]) >>> G.reduce(f) ([2*x, 1], x**2 + y**2 + y) >>> Q, r = _ >>> expand(sum(q*g for q, g in zip(Q, G)) + r) 2*x**4 - x**2 + y**3 + y**2 >>> _ == f True """ poly = Poly._from_expr(expr, self._options) polys = [poly] + list(self._basis) opt = self._options domain = opt.domain retract = False if auto and domain.has_Ring and not domain.has_Field: opt = opt.clone(dict(domain = domain.get_field())) retract = True for i, poly in enumerate(polys): poly = poly.set_domain(opt.domain).rep.to_dict() polys[i] = sdp_from_dict(poly, opt.order) level = len(opt.gens) - 1 Q, r = sdp_div(polys[0], polys[1:], level, opt.order, opt.domain) Q = [ Poly._from_dict(dict(q), opt) for q in Q ] r = Poly._from_dict(dict(r), opt) if retract: try: _Q, _r = [ q.to_ring() for q in Q ], r.to_ring() except CoercionFailed: pass else: Q, r = _Q, _r if not opt.polys: return [ q.as_expr() for q in Q ], r.as_expr() else: return Q, r
[docs] def contains(self, poly): """ Check if ``poly`` belongs the ideal generated by ``self``. Examples ======== >>> from sympy import groebner >>> from sympy.abc import x, y >>> f = 2*x**3 + y**3 + 3*y >>> G = groebner([x**2 + y**2 - 1, x*y - 2]) >>> G.contains(f) True >>> G.contains(f + 1) False """ return self.reduce(poly)[1] == 0
[docs]def poly(expr, *gens, **args): """ Efficiently transform an expression into a polynomial. Examples ======== >>> from sympy import poly >>> from sympy.abc import x >>> poly(x*(x**2 + x - 1)**2) Poly(x**5 + 2*x**4 - x**3 - 2*x**2 + x, x, domain='ZZ') """ options.allowed_flags(args, []) def _poly(expr, opt): terms, poly_terms = [], [] for term in Add.make_args(expr): factors, poly_factors = [], [] for factor in Mul.make_args(term): if factor.is_Add: poly_factors.append(_poly(factor, opt)) elif factor.is_Pow and factor.base.is_Add and factor.exp.is_Integer: poly_factors.append(_poly(factor.base, opt).pow(factor.exp)) else: factors.append(factor) if not poly_factors: terms.append(term) else: product = poly_factors[0] for factor in poly_factors[1:]: product = product.mul(factor) if factors: factor = Mul(*factors) if factor.is_Number: product = product.mul(factor) else: product = product.mul(Poly._from_expr(factor, opt)) poly_terms.append(product) if not poly_terms: result = Poly._from_expr(expr, opt) else: result = poly_terms[0] for term in poly_terms[1:]: result = result.add(term) if terms: term = Add(*terms) if term.is_Number: result = result.add(term) else: result = result.add(Poly._from_expr(term, opt)) return result.reorder(*opt.get('gens', ()), **args) expr = sympify(expr) if expr.is_Poly: return Poly(expr, *gens, **args) if 'expand' not in args: args['expand'] = False opt = options.build_options(gens, args) return _poly(expr, opt)