[Numpy-discussion] Enhancements for NumPy's FFTs

[Charles R Harris]

On Sat, Mar 14, 2009 at 8:26 PM, Sturla Molden <sturla at molden.no> wrote:

> > On Sat, Mar 14, 2009 at 7:23 PM, Sturla Molden <sturla at molden.no> wrote:
>
> > We can't count on C99 at this point. Maybe David will add something so we
> > can use c99 when it is available.
>
> Ok, but most GNU compilers has a __restrict__ extension for C89 and C++
> that we could use. And MSVC has a compiler pragma in VS2003 and a
> __restrict extension in VS2005 later versions.  So we could define a mscro
> RESTRICT to be restrict in ISO C99, __restrict__ in GCC 3 and 4,
> __restrict in recent versions of MSVC, and nothing elsewhere.
>
>
> > I don't have a problem with this, although I not sure what npy type is
> > appropriate without looking. Were you thinking of size_t? I was tempted
> by
> > that. But why is it more efficient? I haven't seen any special
> > instructions
> > at the assembly level, so unless there is some sort of global
> optimization
> > that isn't obvious I don't know where the advantage is.
>
> I may be that my memory serves med badly. I thought I read it here, but it
> does not show examples of different assembly code being generated. So I
> think I'll just leave it for now and experiment with this later.
>
> http://support.amd.com/us/Processor_TechDocs/22007.pdf
>
> Is an npy_intp 64 bit on 64 bit systems?
>
>
Yes, it is the same size as a pointer, but it is signed... Chuck
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