canonise_expression: Used to recognize similar expressions and to possibly simplify them.
Description
It's best to simplify algebraic expression a little before evaluating.
Usage
canonise_expression(x)
Arguments
x
The input is assumed to be a character consisting of one or
more terms. Each term starts with either + or - and after that
contains one or more factors separated by *. Each factor is either
an admix variable, a number or a clause (1 - x) (mind the spaces,
this is how the function f4 outputs), where x is again
either an admix variable or a number.
Everything is pretty much ruined if variable names are numbers or contain
forbidden symbols +, -, *, (, ). Value
A polynomial in a canonical form with no parenthesis or spaces and the
monomials in lexicographical order. If everything is cancelled out then +0.