Physical quantities¶
Physical quantities.

class
sympy.physics.units.quantities.
Quantity
[source]¶ Physical quantity: can be a unit of measure, a constant or a generic quantity.

abbrev
¶ Symbol representing the unit name.
Prepend the abbreviation with the prefix symbol if it is defines.

convert_to
(other)[source]¶ Convert the quantity to another quantity of same dimensions.
Examples
>>> from sympy.physics.units import speed_of_light, meter, second >>> speed_of_light speed_of_light >>> speed_of_light.convert_to(meter/second) 299792458*meter/second
>>> from sympy.physics.units import liter >>> liter.convert_to(meter**3) meter**3/1000

free_symbols
¶ Return free symbols from quantity.

scale_factor
¶ Overall magnitude of the quantity as compared to the canonical units.

Conversion between quantities¶
Several methods to simplify expressions involving unit objects.

sympy.physics.units.util.
convert_to
(expr, target_units)[source]¶ Convert
expr
to the same expression with all of its units and quantities represented as factors oftarget_units
, whenever the dimension is compatible.target_units
may be a single unit/quantity, or a collection of units/quantities.Examples
>>> from sympy.physics.units import speed_of_light, meter, gram, second, day >>> from sympy.physics.units import mile, newton, kilogram, atomic_mass_constant >>> from sympy.physics.units import kilometer, centimeter >>> from sympy.physics.units import convert_to >>> convert_to(mile, kilometer) 25146*kilometer/15625 >>> convert_to(mile, kilometer).n() 1.609344*kilometer >>> convert_to(speed_of_light, meter/second) 299792458*meter/second >>> convert_to(day, second) 86400*second >>> 3*newton 3*newton >>> convert_to(3*newton, kilogram*meter/second**2) 3*kilogram*meter/second**2 >>> convert_to(atomic_mass_constant, gram) 1.66053904e24*gram
Conversion to multiple units:
>>> convert_to(speed_of_light, [meter, second]) 299792458*meter/second >>> convert_to(3*newton, [centimeter, gram, second]) 300000*centimeter*gram/second**2
Conversion to Planck units:
>>> from sympy.physics.units import gravitational_constant, hbar >>> convert_to(atomic_mass_constant, [gravitational_constant, speed_of_light, hbar]).n() 7.62950196312651e20*gravitational_constant**(0.5)*hbar**0.5*speed_of_light**0.5