Re: [Numpy-discussion] What is the sign of nan?

David Cournapeau wrote:

when run tells me:

signbit(NAN) = 0 signbit(-NAN) = -2147483648 signbit((-1) * NAN) = 0 signbit(- NAN + NAN) = -2147483648 signbit(NAN - NAN) = 0

Does not this indicate that signbit(NAN) is undefined ? I guess I am afraid that the glibc NAN is just one type of NAN, and is not the behavior of any NAN,

Bah, this is gibberish. signbit test for the signbit (duh), nothing else, so this is always valid, and never raises a FPE_INVALID: glibc says that copysign is always valid, but I tested with signbit as well, and it does not seem to be raised either for that macro. http://www.gnu.org/software/libc/manual/html_node/FP-Bit-Twiddling.html#FP-B... Funny how far a bug in median can take us :) cheers, David