Daniel J Sebald wrote:
> There may be more to this. I see now that "signgam" is actually an
> external as part of the math library I'm guessing.
No need for guessing --- that's what you have libc/libm manpages for.
> So, if I
> understand this, calling gamma() (i.e., the "old gamma" which is
> actually ln gamma) will set the sign of the gamma function upon
> calling gamma(). How is an optimizing compiler to know that?
It doesn't have to. signgam is a global variable, exported by the
library, and the code reads it.
> Anyway, maybe just avoiding the use of "signgam" in any way is best.
We can't do that. Not on platforms that don't sport a tgamma(), anyway.