Source code for sympy.printing.fcode
"""
Fortran code printer
The FCodePrinter converts single sympy expressions into single Fortran
expressions, using the functions defined in the Fortran 77 standard where
possible. Some useful pointers to Fortran can be found on wikipedia:
http://en.wikipedia.org/wiki/Fortran
Most of the code below is based on the "Professional Programmer\'s Guide to
Fortran77" by Clive G. Page:
http://www.star.le.ac.uk/~cgp/prof77.html
Fortran is a case-insensitive language. This might cause trouble because
SymPy is case sensitive. The implementation below does not care and leaves
the responsibility for generating properly cased Fortran code to the user.
"""
from sympy.core import S, C, Add, N
from sympy.printing.codeprinter import CodePrinter
from sympy.printing.precedence import precedence
[docs]class FCodePrinter(CodePrinter):
"""A printer to convert sympy expressions to strings of Fortran code"""
printmethod = "_fcode"
_default_settings = {
'order': None,
'full_prec': 'auto',
'assign_to': None,
'precision': 15,
'user_functions': {},
'human': True,
'source_format': 'fixed',
}
_implicit_functions = set([
"sin", "cos", "tan", "asin", "acos", "atan", "atan2", "sinh",
"cosh", "tanh", "sqrt", "log", "exp", "erf", "Abs", "sign", "conjugate",
])
def __init__(self, settings=None):
CodePrinter.__init__(self, settings)
self._init_leading_padding()
assign_to = self._settings['assign_to']
if isinstance(assign_to, basestring):
self._settings['assign_to'] = C.Symbol(assign_to)
elif not isinstance(assign_to, (C.Basic, type(None))):
raise TypeError("FCodePrinter cannot assign to object of type %s" %
type(assign_to))
def _rate_index_position(self, p):
"""function to calculate score based on position among indices
This method is used to sort loops in an optimized order, see
CodePrinter._sort_optimized()
"""
return -p*5
def _get_statement(self, codestring):
return codestring
def _init_leading_padding(self):
# leading columns depend on fixed or free format
if self._settings['source_format'] == 'fixed':
self._lead_code = " "
self._lead_cont = " @ "
self._lead_comment = "C "
elif self._settings['source_format'] == 'free':
self._lead_code = ""
self._lead_cont = " "
self._lead_comment = "! "
else:
raise ValueError(
"Unknown source format: %s" % self._settings[
'source_format']
)
def _pad_leading_columns(self, lines):
result = []
for line in lines:
if line.startswith('!'):
result.append(self._lead_comment + line[1:].lstrip())
else:
result.append(self._lead_code + line)
return result
def _get_loop_opening_ending(self, indices):
"""Returns a tuple (open_lines, close_lines) containing lists of codelines
"""
open_lines = []
close_lines = []
for i in indices:
# fortran arrays start at 1 and end at dimension
var, start, stop = map(self._print,
[i.label, i.lower + 1, i.upper + 1])
open_lines.append("do %s = %s, %s" % (var, start, stop))
close_lines.append("end do")
return open_lines, close_lines
[docs] def doprint(self, expr):
"""Returns Fortran code for expr (as a string)"""
# find all number symbols
self._number_symbols = set()
# keep a set of expressions that are not strictly translatable to
# Fortran.
self._not_supported = set()
lines = []
from sympy.functions import Piecewise
if isinstance(expr, Piecewise):
# support for top-level Piecewise function
for i, (e, c) in enumerate(expr.args):
if i == 0:
lines.append("if (%s) then" % self._print(c))
elif i == len(expr.args) - 1 and c is True:
lines.append("else")
else:
lines.append("else if (%s) then" % self._print(c))
lines.extend(
self._doprint_a_piece(e, self._settings['assign_to']))
lines.append("end if")
else:
lines.extend(
self._doprint_a_piece(expr, self._settings['assign_to']))
# format the output
if self._settings["human"]:
frontlines = []
if len(self._not_supported) > 0:
frontlines.append("! Not Fortran:")
for expr in sorted(self._not_supported, key=self._print):
frontlines.append("! %s" % repr(expr))
for name, value in sorted(self._number_symbols, key=str):
frontlines.append("parameter (%s = %s)" % (str(name), value))
frontlines.extend(lines)
lines = frontlines
lines = self.indent_code(lines)
lines = self._wrap_fortran(lines)
result = "\n".join(lines)
else:
lines = self.indent_code(lines)
lines = self._wrap_fortran(lines)
result = self._number_symbols, self._not_supported, "\n".join(
lines)
del self._not_supported
del self._number_symbols
return result
def _print_Add(self, expr):
# purpose: print complex numbers nicely in Fortran.
# collect the purely real and purely imaginary parts:
pure_real = []
pure_imaginary = []
mixed = []
for arg in expr.args:
if arg.is_number and arg.is_real:
pure_real.append(arg)
elif arg.is_number and arg.is_imaginary:
pure_imaginary.append(arg)
else:
mixed.append(arg)
if len(pure_imaginary) > 0:
if len(mixed) > 0:
PREC = precedence(expr)
term = Add(*mixed)
t = self._print(term)
if t.startswith('-'):
sign = "-"
t = t[1:]
else:
sign = "+"
if precedence(term) < PREC:
t = "(%s)" % t
return "cmplx(%s,%s) %s %s" % (
self._print(Add(*pure_real)),
self._print(-S.ImaginaryUnit*Add(*pure_imaginary)),
sign, t,
)
else:
return "cmplx(%s,%s)" % (
self._print(Add(*pure_real)),
self._print(-S.ImaginaryUnit*Add(*pure_imaginary)),
)
else:
return CodePrinter._print_Add(self, expr)
def _print_Function(self, expr):
name = self._settings["user_functions"].get(expr.__class__)
eargs = expr.args
if name is None:
from sympy.functions import conjugate
if expr.func == conjugate:
name = "conjg"
else:
name = expr.func.__name__
if hasattr(expr, '_imp_') and isinstance(expr._imp_, C.Lambda):
# inlined function.
# the expression is printed with _print to avoid loops
return self._print(expr._imp_(*eargs))
if expr.func.__name__ not in self._implicit_functions:
self._not_supported.add(expr)
else:
# convert all args to floats
eargs = map(N, eargs)
return "%s(%s)" % (name, self.stringify(eargs, ", "))
_print_factorial = _print_Function
def _print_ImaginaryUnit(self, expr):
# purpose: print complex numbers nicely in Fortran.
return "cmplx(0,1)"
def _print_int(self, expr):
return str(expr)
def _print_Mul(self, expr):
# purpose: print complex numbers nicely in Fortran.
if expr.is_number and expr.is_imaginary:
return "cmplx(0,%s)" % (
self._print(-S.ImaginaryUnit*expr)
)
else:
return CodePrinter._print_Mul(self, expr)
_print_Exp1 = CodePrinter._print_NumberSymbol
_print_Pi = CodePrinter._print_NumberSymbol
def _print_Pow(self, expr):
PREC = precedence(expr)
if expr.exp == -1:
return '1.0/%s' % (self.parenthesize(expr.base, PREC))
elif expr.exp == 0.5:
if expr.base.is_integer:
# Fortan intrinsic sqrt() does not accept integer argument
if expr.base.is_Number:
return 'sqrt(%s.0d0)' % self._print(expr.base)
else:
return 'sqrt(dble(%s))' % self._print(expr.base)
else:
return 'sqrt(%s)' % self._print(expr.base)
else:
return CodePrinter._print_Pow(self, expr)
def _print_Rational(self, expr):
p, q = int(expr.p), int(expr.q)
return "%d.0d0/%d.0d0" % (p, q)
def _print_Float(self, expr):
printed = CodePrinter._print_Float(self, expr)
e = printed.find('e')
if e > -1:
return "%sd%s" % (printed[:e], printed[e + 1:])
return "%sd0" % printed
def _print_Indexed(self, expr):
inds = [ self._print(i) for i in expr.indices ]
return "%s(%s)" % (self._print(expr.base.label), ", ".join(inds))
def _print_Idx(self, expr):
return self._print(expr.label)
def _wrap_fortran(self, lines):
"""Wrap long Fortran lines
Argument:
lines -- a list of lines (without \\n character)
A comment line is split at white space. Code lines are split with a more
complex rule to give nice results.
"""
# routine to find split point in a code line
my_alnum = set("_+-.0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ_")
my_white = set(" \t()")
def split_pos_code(line, endpos):
if len(line) <= endpos:
return len(line)
pos = endpos
split = lambda pos: \
(line[pos] in my_alnum and line[pos - 1] not in my_alnum) or \
(line[pos] not in my_alnum and line[pos - 1] in my_alnum) or \
(line[pos] in my_white and line[pos - 1] not in my_white) or \
(line[pos] not in my_white and line[pos - 1] in my_white)
while not split(pos):
pos -= 1
if pos == 0:
return endpos
return pos
# split line by line and add the splitted lines to result
result = []
if self._settings['source_format'] == 'free':
trailing = ' &'
else:
trailing = ''
for line in lines:
if line.startswith(self._lead_comment):
# comment line
if len(line) > 72:
pos = line.rfind(" ", 6, 72)
if pos == -1:
pos = 72
hunk = line[:pos]
line = line[pos:].lstrip()
result.append(hunk)
while len(line) > 0:
pos = line.rfind(" ", 0, 66)
if pos == -1 or len(line) < 66:
pos = 66
hunk = line[:pos]
line = line[pos:].lstrip()
result.append("%s%s" % (self._lead_comment, hunk))
else:
result.append(line)
elif line.startswith(self._lead_code):
# code line
pos = split_pos_code(line, 72)
hunk = line[:pos].rstrip()
line = line[pos:].lstrip()
if line:
hunk += trailing
result.append(hunk)
while len(line) > 0:
pos = split_pos_code(line, 65)
hunk = line[:pos].rstrip()
line = line[pos:].lstrip()
if line:
hunk += trailing
result.append("%s%s" % (self._lead_cont, hunk))
else:
result.append(line)
return result
[docs] def indent_code(self, code):
"""Accepts a string of code or a list of code lines"""
if isinstance(code, basestring):
code_lines = self.indent_code(code.splitlines(True))
return ''.join(code_lines)
free = self._settings['source_format'] == 'free'
code = [ line.lstrip(' \t') for line in code ]
inc_keyword = ('do ', 'if(', 'if ', 'do\n', 'else')
dec_keyword = ('end do', 'enddo', 'end if', 'endif', 'else')
increase = [ int(any(map(line.startswith, inc_keyword)))
for line in code ]
decrease = [ int(any(map(line.startswith, dec_keyword)))
for line in code ]
continuation = [ int(any(map(line.endswith, ['&', '&\n'])))
for line in code ]
level = 0
cont_padding = 0
tabwidth = 3
new_code = []
for i, line in enumerate(code):
if line == '' or line == '\n':
new_code.append(line)
continue
level -= decrease[i]
if free:
padding = " "*(level*tabwidth + cont_padding)
else:
padding = " "*level*tabwidth
line = "%s%s" % (padding, line)
if not free:
line = self._pad_leading_columns([line])[0]
new_code.append(line)
if continuation[i]:
cont_padding = 2*tabwidth
else:
cont_padding = 0
level += increase[i]
if not free:
return self._wrap_fortran(new_code)
return new_code
[docs]def fcode(expr, **settings):
"""Converts an expr to a string of Fortran 77 code
Parameters
==========
expr : sympy.core.Expr
a sympy expression to be converted
assign_to : optional
When given, the argument is used as the name of the
variable to which the Fortran expression is assigned.
(This is helpful in case of line-wrapping.)
precision : optional
the precision for numbers such as pi [default=15]
user_functions : optional
A dictionary where keys are FunctionClass instances and values
are there string representations.
human : optional
If True, the result is a single string that may contain some
parameter statements for the number symbols. If False, the same
information is returned in a more programmer-friendly data
structure.
source_format : optional
The source format can be either 'fixed' or 'free'.
[default='fixed']
Examples
========
>>> from sympy import fcode, symbols, Rational, pi, sin
>>> x, tau = symbols('x,tau')
>>> fcode((2*tau)**Rational(7,2))
' 8*sqrt(2.0d0)*tau**(7.0d0/2.0d0)'
>>> fcode(sin(x), assign_to="s")
' s = sin(x)'
>>> print fcode(pi)
parameter (pi = 3.14159265358979d0)
pi
"""
# run the printer
printer = FCodePrinter(settings)
return printer.doprint(expr)
[docs]def print_fcode(expr, **settings):
"""Prints the Fortran representation of the given expression.
See fcode for the meaning of the optional arguments.
"""
print fcode(expr, **settings)
