[Numpy-discussion] Test error with ATLAS, Windows 64 bit

[Charles R Harris]

On Mon, Apr 14, 2014 at 4:40 PM, Matthew Brett <matthew.brett at gmail.com>wrote:

> Hi,
>
> On Mon, Apr 14, 2014 at 2:58 PM, Charles R Harris
> <charlesr.harris at gmail.com> wrote:
> >
> >
> >
> > On Mon, Apr 14, 2014 at 3:38 PM, Matthew Brett <matthew.brett at gmail.com>
> > wrote:
> >>
> >> Hi,
> >>
> >> On Mon, Apr 14, 2014 at 2:02 PM, Julian Taylor
> >> <jtaylor.debian at googlemail.com> wrote:
> >> > The official numpy mingw binaries do not have all these math issues.
> >> > Only the VC builds do.
> >> > As mingw is fine the functions must be somewhere in the windows API
> but
> >> > no-one has contributed a fix for the VC builds to numpy yet.
> >>
> >> I'm building with mingw-w64.
> >>
> >> It looks like this works as expected from this test:
> >>
> >> #include <math.h>
> >> #include <stdio.h>
> >>
> >> int main() {
> >>     double z;
> >>     z = expm1(-0.0);
> >>     printf("Result %f\n", z);
> >> }
> >>
> >> (prints -0).
> >>
> >> as does this (modified from core/src/npymath/npy_math.c.src):
> >>
> >> #include <stdio.h>
> >>
> >> double npy_expm1(double x)
> >> {
> >>     if (isinf(x) && x > 0) {
> >>         return x;
> >>     }
> >>     else {
> >>         const double u = exp(x);
> >>
> >>         if (u == 1.0) {
> >>             return x;
> >>         } else if (u - 1.0 == -1.0) {
> >>             return -1;
> >>         } else {
> >>             return (u - 1.0) * x/log(u);
> >>         }
> >>     }
> >> }
> >>
> >> int main() {
> >>     double z;
> >>     z = npy_expm1(-0.0);
> >>     printf("Result %f\n", z);
> >> }
> >>
> >> Sorry for my ignorance, but where does the `HAVE_EXPM1` symbol come
> from?
> >>
> >
> > Remember all configuration output at the beginning of the build? One of
> > those tries to link 'expm1{f, , l}' and sets the value of
> 'HAVE_EXPM1{F,,L}'
> > accordingly. You can find the result in the `config.h` file in the build
> > directory.
>
> Ah - thanks - that got me going - somewhere.
>
> I noticed that HAVE_EXPM1 is not defined in any of OSX, my Windows
> build, Debian config.h - is that expected?
>

It's defined for me,  gcc version 4.8.2 on fedora 20. I'm surprised that
Debian doesn't show it, what compiler version does Debian provide?

We could always borrow the boost version, although it uses the Kahan sum
for the series.

Chuck
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