[Numpy-discussion] long double woes on win32

Charles R Harris charlesr.harris@gmail....
Sat Aug 16 16:02:16 CDT 2008


On Sat, Aug 16, 2008 at 2:46 PM, David Cournapeau <cournape@gmail.com>wrote:

> On Sat, Aug 16, 2008 at 2:07 PM, Charles R Harris
> <charlesr.harris@gmail.com> wrote:
> >
> >
> > There is seems to be a problem in defining the functions called for the
> > different types.
>
> I don't know enough about this part of the code to be sure about the
> whole function calls stack, but I would guess this is not surprising
> and even expected: you force long double to be double, but you still
> call the long double function if you do np.exp, so this cannot work.


Part of the problem is that the loops/functions called depend on the
typecode, i.e., dtype.char, which stays as 'g' even when the underlying type
is float64. We can't really fix that because the C-API still allows folks to
create arrays using the typecode and we would have to fudge things so the
right "wrong" descr was returned. Ugly, and a left over from numeric which
defined types to match the c types instead of the precision. Maybe we should
rewrite in FORTRAN ;) Anyway, I think the easiest solution might be to use
npy_func internally and add a -DNOLONGDOUBLE flag to override the values
returned by the distutils test code. Whether we should try such a big
modification before 1.2 is another question.

Chuck
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