bug in parser

[fjames86]

incorrectly parses terms with multiple signs, e.g.

{1 ++ 4x} -> #{2 + 4x}

{1 -- 4x} -> #{4x}

Something strange happening here...

[fjames86]

in fact, also applies to any negative sign, e.g. #{1 - 4x + 7} -> #{-6 -4x}

[fjames86]

the above issue is now fixed. but the double sign problem remains and looks to be difficult to fix. double signs should not be allowed anyyway

[fjames86]

could be fixed by adding a 2nd accumulator to build-monomial, so there is a separate accumulator for the total polynomial (which gets summed) and the monomial (which gets multiplied).

[fjames86]

now fixed, so that e.g. #{-4} -> #{-4} instead of #{-3} as before, similarly #{++++} -> #{0}. However, multiple signs still aren't really correctly handled, since multiple negative signs don't work. so #{--3} -> #{-3} instead of #{3}.

[fjames86]

parser can't deal with fractional coefficients, although they are perfectly permissible. probably should add this functionality to the parser.

[fjames86]

could also add arbitrary expressions for exponents, e.g. #{x ^ (3*4)} -> #{x^7}

[fjames86]

bug fixed. extensions to the parser could be added at a later date but are not essential at this time.