Le 26 juin 2012 ? 07:05, Stavros Macrakis a ?crit :
> Subst is purely syntactic. Probably a bad design, but there it is. Try "at".
>
> -s
This is not really a problem of subst, in that case,
integrate('diff(f(t)*diff(g(t),t),t),t,sqrt(beta),sqrt(alpha));
just returns a formula that is not syntactically correct and prevent further calculations.
Using "at" won't help at least when you have to evaluate the formula in a real life context.
one solution is to replace the above integral by
integrate(...,t,sqrt(beta),0)+integrate(...,t,0,sqrt(alpha));
if it ever makes sense. defint may also help.
JL