symmath.expr

exception symmath.expr.SymmathError

Bases: ValueError

class symmath.expr.Expr(other=None, tolerance=1e-08)

Class used for symbolic computations. Introduction to symmath describes what operations this class supports.

terms

A mapping from symbol names to their coefficients.

tolerance

Numbers smaller than the tolerance in absolute value are converted to 0.

scalar()

If x contains no symbols, x.scalar() returns a regular float equal to the scalar part of x. Otherwise an exception is raised.

>>> a = sym('a')
>>> x = a + 3
>>> x.scalar()
Traceback (most recent call last):
  ...
SymmathError: Not a scalar
>>> x -= a
>>> x
Expr(3)
>>> x.scalar()
3

substitue(symbol, arg)

Replace all occurances of symbol with arg.

>>> from symmath import sym
>>> x = sym("x")
>>> y = sym("y")
>>> z = sym("z")
>>> e = 2 * x + y + 1
>>> e.substitue("x", y + z)
>>> print(e)
3 y + 2 z + 1

symmath.expr.sym(symbol)

Create an expression containing just the given symbol.

>>> sym('a')
Expr(a)