[SciPy-User] Single precision FFT insufficiently accurate.

David Cournapeau cournape@gmail....
Mon Jun 28 05:38:37 CDT 2010


On Mon, Jun 28, 2010 at 3:05 PM, Anne Archibald
<aarchiba@physics.mcgill.ca> wrote:

>
> I guess the question here is where we do the conversion - of course it
> is easiest to do that outside all the FFT loops. But it seems like
> that iteration over all-but-one dimension of the array will often need
> to copy the data anyway to get a contiguous 1d array; I'd say that's
> the natural place to do upconverstion when necessary. (Though, does
> FFTPACK provide strided/iterated FFTs? My only compiled-language
> experience is with FFTW, which does.)
>
> Failing that, I still think we're better providing single-precision
> FFTs for easy factorizations than for none at all; my basic point was
> that the FFT's behaviour already depends very strongly on the size of
> the input array, so this is not a new form of "data dependence".

Right, this significantly weakens my objection.

David


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