Re: [pooma-dev] FFT

[Richard Guenther]

On Sat, 8 Feb 2003, Gasper Tkacik wrote:

> Hi Guenther!
>
> Thank you for the advice. I took a look at the code. However, I somehow
> cannot get the correct results when I use Real-to-Complex transform
> (rfftw) on 2D arrays. Is it possible that this is so because the
> algorithm does in-place transform and lays out the values in the
> half-complex packing? Has this been tested on rfftw or has it only been
> tested with complex-to-complex stuff? I am afraid to use complex because
> of the overhead.

I dont know at all - never used the fftw wrapper myself. But reading your
description of operation I think your analysis is right that pooma cannot
know about n*real to n/2*complex data transform. Maybe it does cope with
that, but that need to be explicitly handled in the wrapper.

I'd suggest looking at the source and maybe fixing/extending it.

Richard.

> Best regards, Gasper.
>
> Richard Guenther wrote:
>
> >On Thu, 6 Feb 2003, Gasper Tkacik wrote:
> >
> >
> >
> >>Hello everybody!
> >>
> >>Is there any support for FFT operations in Pooma? For example, given a
> >>Array<double, 3>, is there any preferred way of doing FFT?
> >>If not, is there any way of doing it in parallel with the constructs
> >>that Pooma provides?
> >>
> >>
> >
> >Try looking at src/Transform/WrapFFTW.h which seems to make use of libfftw
> >to do FFT.
> >
>
>