On Wed, Apr 27, 2011 at 4:14 AM, Dan Goodman <dg.gm...@thesamovar.net> wrote: > Hi, > > On 26/04/2011 15:40, Mihai Badoiu wrote: >> I have terrible performance for multiplication when one number gets very >> close to zero. I'm using cython by writing the following code: > > This might be an issue with denormal numbers: > > http://en.wikipedia.org/wiki/Denormal_number > > I don't know much about them though, so I can't advise any further than > that...
This indeed sounds like it. Mihai, which CPU are you using ? Pentium4 are especially known to have terrible (read order of magnitude slower) performance with denormal numbers. There is unfortunately no simple way to know whether a float is denormal or not in python, but since you are using cython, if you are under posix you should be able to use fpclassify to check this, From there, if you see a difference between cython/python and C, it will be easier to debug. cheers, David -- http://mail.python.org/mailman/listinfo/python-list
