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- To: eigen@xxxxxxxxxxxxxxxxxxx
- Subject: Re: [eigen] FFT for Eigen
- From: Benoit Jacob <jacob.benoit.1@xxxxxxxxx>
- Date: Tue, 19 May 2009 14:49:44 +0200
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I can believe that this is probably a very efficient storage scheme.
We could offer this as an option if really it's not too hard to
implement (i didn't start thinking about this).
The default should remain the current for many reasons, but as an
option why not.
Cheers,
Benoit
2009/5/19 Márton Danóczy <marton78@xxxxxxxxx>:
>> I concur: I don't think that it would be very useful to have complex
>> matrices with the real and imaginary parts stored separately. Most
>> operations -- and the more costly ones -- would run slower in such a
>> scheme. The basic issue here is memory locality.
>
> What about storing them packet by packet? That is, in case of floats,
> four real parts followed by four imaginary parts. That would not be
> too hard to implement and vectorization of component-wise operations
> would be trivial. And I think even FFTW can handle that using the guru
> interface, by setting up a split fft plan with a stride of
> 2*packetsize.
>
> Marton
>
>
>