[GRASS5] i.fft segemntation fault

Glynn Clements glynn.clements at virgin.net
Fri Jun 11 08:10:18 EDT 2004

Stephan Holl wrote:

> > The memory requirements could be reduced to two doubles per cell
> > (without scaling up to a power of two) if i.fft used FFTW directly,
> > rather than using the fft() interface. Or to two floats per cell if
> > FFTW was built to use float instead of double.
> As this seems to be an option for reducing the memory-needs a little, is
> this a doable task? I think it would be benefit when FFTW is used
> directly instead of fft(). Correct me when I am wrong, please...
> If so, how much work would that be?

Not much; the fft() function itself is trivial, and much of that is
copying the data between the separate real/imaginary arrays and the
single complex array used by FFTW, which wouldn't be necessary if you
were calling FFTW directly.

Note: the fft() function is in src/libes/gmath/fft.c.

Glynn Clements <glynn.clements at virgin.net>

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