The simplest way to check for a "valid" answer may be to evaluate it and see
if it comes to the right answer.
You can use errcatch to catch error exits, like divide by zero.
> -----Original Message-----
> From: maxima-bounces at math.utexas.edu
> [mailto:maxima-bounces at math.utexas.edu] On Behalf Of Juhana
> Antero Yrj?l?
> Sent: Tuesday, October 09, 2007 9:14 AM
> To: Stavros Macrakis
> Cc: maxima at math.utexas.edu
> Subject: Re: [Maxima] A simple way to parse/check equations?
>
> Hi again
> Thank you for your speedy responses. This is not a school
> work is a real
> job related stuff. This function is needed in an online learning
> enviroment, where it checks that student has valid answer(no wrong
> function calls and stuff like that). So it takes about pretty
>.....