Guido van Rossum wrote:
> Well, the Python API in the math module should always be called copysign(). :-)
> 
> And what to do if neither is present? Are there any systems without it?

takes care of it. It's a macro to define a function which accepts two
floats and returns a float: FUNC2(funcname, func, docstring).

On Windows _copysign is always defined and on other systems we can use
HAVE_COPYSIGN. I added it to configure.in a while ago.

Christian