From: Rainer Schöpf <rainer.schoepf@gm...>  20121117 13:59:06

This expression: p2:=1/(sqrt(dx)*sqrt(cx)*sqrt(bx)*sqrt(ax)*(a*ba*xb*x+x**2)); takes forever to integrate. With the new switch trintsubst (to trace only the substitutions) you see that more and more complex substitutions are tried, without any reasonable result: load_package int; on trintsubst; int(p2,x); As you can see, at one point there appears the square root of polynomials of hyperbolic functions, which isn't a sensible way to go, in my opinion. I added another new switch nointsubst to switch off the substitution attempts entirely. With "on nointsubst", the integral is returned unevaluated within a very short time. I think this needs some heuristics to stop these substitutions when they lead to overly complicated integrands. Maybe stop when surds or exponentials with transcendental functions appear. Any ideas? Rainer 