Harald,
thank you very much for your bugreport. I changed the code, the problem was
exactly what you guessed.
The sources will be available on sourceforge, hope in few days or a couple
of weeks. The address will be
https://sourceforge.net/projects/mathassistant/
BTW while playing with your program I found a bug:
> take the derivative of x^3*exp(aa*x^2) - there seems to be some
> recursion problem. Probably because you use aa internally for something
> (pattern matching?).
I changed the pattern matching and also, I do not allow multichar constants.
On the other hand, we are able differentitate something like
a(x^3)*exp(2*x) (the derivative of a function remains unevaluated of
course)
I sorry that I answer so late. I wrote the answer before, but for a strange
reason, my answer remained in draft folder. Probably I started to play with
little daughter when replying your mail and forgot to send it.
Thank you again.
Robert
> Other multichar symbols (like aba) work just fine.
>
> HTH,
> Harald
>