Improper integral

[parisse]

Looks like a print bug, (-1)^.5 should not be converted to sqrt(-1). I will change that at least for giac.
Regarding fractional powers, there is no good solution, but I strongly believe the current behavior is the best compromise (of course the error message can be changed if you have a good suggestion, perhaps something that would suggest using surd/NTHROOT). I'm fixing a small bug, so that int(1/surd(x-1,5),x,1,33) will return 20, and int(1/surd(x-1,5),x,0,33) will return 75/4.