http://gcc.gnu.org/bugzilla/show_bug.cgi?id=57749
--- Comment #4 from Vittorio Zecca <zeccav at gmail dot com> --- I am happy to refresh my complex analysis study of long ago. The singularity of log(x) in zero is not essential. Essential singularity means the Laurent seriesis infinite in both directions? z**-k and z**+k roughly, but log(z) Laurent series is infinite only for z**+k. I hope to remember correctly. But exp(y*log(x)) may well be essential, however. Anyway I am not sure this is an essential (forgive the pun) reason to raise an exception Also I do not understand the different behaviour with different levels of optimization, and I confirm the a.out executable runs fine under valgrind. And the code runs fine with Intel ifort. And I really do not see how complex zero raised to a positive power should raise an exception. 2013/6/29 anlauf at gmx dot de <gcc-bugzi...@gcc.gnu.org> > http://gcc.gnu.org/bugzilla/show_bug.cgi?id=57749 > > --- Comment #3 from Harald Anlauf <anlauf at gmx dot de> --- > (In reply to Vittorio Zecca from comment #2) > > I believe -O0 is the default optimization level, so it is important. > > > > Of course the code I sent you is a fragment from a much larger program, > > kind of c**x with c complex and x real. It is not possible to make x > > into an integer. > > > > When x is zero and y is real, x**y is singular for y<=0, right? > > I think you are missing the intricacies of complex arithmetics. > > x**y = exp (y * log(x)) has an *essential singularity* at x=0, > which is the starting point of a branch cut (usually the negative > real axis). See also cpow(3). > > The man page for pow(3) covers only real arithmetics and does not apply. > > > Also, I do not understand why I get SIGFPE on either zero or invalid > > -ffpe-trap suboption, > > but this is a lesser issue. > > A quick search did not turn up any result whether IEEE specifies > a defined behavior for your case. Maybe you are more successful. > I also could not find anything in the Fortran standard. > > -- > You are receiving this mail because: > You reported the bug. >
