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Blitz Support : |
From: Julian C. Cummings (cummings_at_[hidden])
Date: 2004-09-02 14:21:45
Hello Othmar,
Presumably the proper data alignment can be obtained by using an appropriate
compiler flag. You might want to look at how the fftw library and the
fftw++ wrapper package are being compiled to see what special compiler
options (if any) are being used to control data alignment. Using the same
options when building your application with fftw and blitz should be all
that is required. I believe that 8-byte alignment of doubles implies
16-byte alignment of complex<double> objects, since these are concrete data
types.
Regards, Julian C.
Dr. Julian C. Cummings
Staff Scientist, CACR/Caltech
(626) 395-2543
cummings_at_[hidden]
> -----Original Message-----
> From: blitz-support-bounces_at_[hidden]
> [mailto:blitz-support-bounces_at_[hidden]] On Behalf Of Othmar Frey
> Sent: Thursday, September 02, 2004 3:14 AM
> To: blitz-support_at_[hidden]
> Subject: [Blitz-support] FFTW and Blitz++, 16-byte aligned Vector
>
>
> Hi.
>
> I am using (or rather trying to use) the fftw library in combination
> with Blitz++.
>
> I've learned that the arrays of complex data passed to fftw must be
> 16-byte aligned
> to exploit the "Single Instruction Multiple Data" support of fftw.
>
> Is there a way to make a Vector<complex<double> > be 16-byte
> aligned in
> memory?
>
> Until now, I used the fftw++ wrapper class by John C. Bowman in
> combination with his
> Array class (http://www.math.ualberta.ca/~bowman/Array.h)
> then created a
> blitz::Vector
> from preexisting memory by passing a pointer to an array of Bowman's
> Array class.
> But I am not that happy with this kind of "solution".
>
> Any suggestions?
>
> Best regards
>
> Othmar
>
> --
> --------------------------------------------------------------
> ---------
> Othmar Frey Remote Sensing
> Laboratories RSL
> ofrey_at_[hidden] University of Zurich
> http://www.geo.unizh.ch/~ofrey Winterthurerstrasse 190
> phone +41 44 635 51 64 CH-8057 Zurich
> fax +41 44 635 68 46 Switzerland
> --------------------------------------------------------------
> ---------
>
>
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