[GiNaC-list] Problem simplifying exponents in polynomials

[Chris.Dams at mi.infn.it]

Dear Gerry,

> I've not managed to make the expand() & collect() functions do this, it
> seems to not want to perform something like:
>
> e^t*e^(1-t)=e^1

Yes, this is not included in the automatic simplifications, so you will
have to do it yourself. In cases like this I usually use a function that I
call simplify and that is defined as

ex simplify(const ex&x,const exmap &m)
{  if (is_a<mul>(x))
   {  ex y=x;
      ex xprev;
      do
      {  xprev = y;
         y = y.subs(m, subs_options::subs_algebraic).expand();
      } while(xprev != y);
      return y;
   }
   if (is_a<add>(x))
   {  exvector ev;
      for(size_t i=0;i<x.nops();++i)
         ev.push_back(simplify(x.op(i), m));

      return add(ev);
   }
   return x;
}

This can be used by doing
exmap m;
m[power(e,wild(0))*power(e,wild(1))] = power(e, wild(0)+wild(1));
f = simplify(f, m)

Good luck,
Chris