Ray writes (this is good information for a neophyte to know!):
"It uses the internal variable yx and wants to solve the equation yx = exp(sqrt(x)) for x. I guess it needs to know the sign of yx to solve this."
My naive comments:
1. Minimal help to user: include this message inside of integrate() - user interaction when asking a question about an internal variable yx whose function is normally hidden from the user.
2. More help to user: examine range of integration variable (x), determine if sign of integrand is constant over that integration range, and if so, determine the sign of yx from that information.
3. Even more help: split up the integral into a sum of integrals, for each of which one can determine the sign of yx.
Ted Woollett