Hi,
On Mon, Apr 14, 2014 at 3:55 PM, Charles R Harris
<charlesr.har...@gmail.com> wrote:
>
>
>
> On Mon, Apr 14, 2014 at 4:40 PM, Matthew Brett <matthew.br...@gmail.com>
> wrote:
>>
>> Hi,
>>
>> On Mon, Apr 14, 2014 at 2:58 PM, Charles R Harris
>> <charlesr.har...@gmail.com> wrote:
>> >
>> >
>> >
>> > On Mon, Apr 14, 2014 at 3:38 PM, Matthew Brett <matthew.br...@gmail.com>
>> > wrote:
>> >>
>> >> Hi,
>> >>
>> >> On Mon, Apr 14, 2014 at 2:02 PM, Julian Taylor
>> >> <jtaylor.deb...@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?
Yes, sorry - I had an old version of numpy on Debian. It is defined for 1.8.1
It's not defined on OSX because it is defined in pyconfig.h (via Python.h).
I was wrong, it is defined in config.h for Windows, I'm not sure how I
missed that. Now I'm trying to understand why it's giving different
results from the tiny test function above,
Cheers,
Matthew
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