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

[Matthew Brett]

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?

Cheers,

Matthew