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Blitz Support : |
From: Einar Otnes (eiot_at_[hidden])
Date: 2003-11-27 02:21:09
Instead of writing new FFT's for Blitz, is it not better to write
interfaces to already existing FFT libraries? FFTW is the first library
that come to my mind, which is very good and well tested. It is not
restricted to radix-2. It might be a problem that it is restricted by GPL
which is more strict than the Blitz artistic licence.
Thanks,
Einar
"Julian C. Cummings"
<cummings_at_[hidden] To: "'Support list for Blitz++'" <blitz-support_at_[hidden]>
> cc: (bcc: Einar Otnes)
Sent by: Subject: RE: [Blitz-support] FFT using blitz
blitz-support-bounces_at_oonu
merics.org
26.11.2003 22:16
Please respond to
cummings; Please respond
to Support list for
Blitz++
Navneet,
Your request is very timely, as I am just now getting serious about
gathering up user submissions for blitz algorithms and adding them to the
blitz distribution. Another blitz user submitted some code (based on
Numerical Recipes, I think) for doing FFT's, along with other types of
transforms and linear algebra routines. I have been playing with this
submission for a little while, trying to debug some parts of it and clean
up
the interface.
It is a bit overly general because the code author was attempting to target
multiple array packages, but this can be changed. Also, the routines are
limited to radix-2, do not attempt to distinguish between real or complex
transforms, and assume that you are transforming along the rows of the
given
Array. I think there needs to be additional support added for
automatically
transforming along any Array dimension.
If you have a nice interface in mind for how to apply FFT's to blitz
Arrays,
I encourage you to submit it as a Request for Enhancement (RFE) on the
blitz
sourceforge website. I can probably modify the previously submitted FFT
routines to match whatever interface you feel is reasonable, and then we
can
add support for real FFTs, non-radix-2 transforms, etc.
Also, if there is a better starting point than Numerical Recipes for the
basic code, please make a suggestion or submit some code.
Regards, Julian C.
P.S. I did something like this for the Pooma package in the past. In that
case, I found it sensible to cast the FFT support in the form of a class in
which the type (real or complex) and the dimensionality were template
parameters. The class provided data members to store the wavetable (exp or
sin/cos factors) and temporary workspace needed, with an initialize
function
to set these up. It also provided a transform method with parameters to
indicate the direction of the transform (forward or inverse) and the
dimension to transform. This might be an appropriate model for FFTs of
blitz Arrays as well.
> -----Original Message-----
> From: blitz-support-bounces_at_[hidden]
> [mailto:blitz-support-bounces_at_[hidden]] On Behalf Of
> Navneet Dalal
> Sent: Tuesday, November 25, 2003 8:26 AM
> To: Support list for Blitz++
> Subject: [Blitz-support] FFT using blitz
>
>
> Hi everybody,
>
> I need to use FFT for (2D) blitz's arrays. So I would like to know if
> someone has implement FFT in blitz arrays before -- or I am
> on my own?
>
> thanks in advance...
> navneet
>
> --
> Navneet DALAL http://www.inrialpes.fr/lear/people/Dalal
>
> INRIA Rhone-Alpes Ph(work): +33 (0)476 61 54 97
> ZIRST-655, av. de l'Europe - 38334 FAX : +33 (0)476 61 54 54
> Montbonnot St. Martin, France Mobile : +33 (0)677 54 33 33
> _______________________________________________
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> http://www.oonumerics.org/mailman/listinfo.cgi> /blitz-support
>
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