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From: | David Bateman |
Subject: | Re: More efficient MEX or MEX-like interface |
Date: | Tue, 30 Sep 2008 10:51:35 +0200 |
User-agent: | Thunderbird 2.0.0.17 (X11/20080926) |
Fredrik Lingvall wrote:
Yes, Octave calls lapack/blas functions like [cz]GEMM, for complex arguments. Greping the matlab libraries withDoes this mean that BLAS/LAPACK expects complex data stored in the same way as complex data is currently stored in Octave?
nm -C --dynamic libmwnumerics.so | grep [gG][eE][mM][mM] gives U dgemm_ U sgemm_ U zgemm_So it appears that the double precision complex matrix multiple is linked in but the single precision version isn't. I'd think this means that in fact ZGEMM is used by the SuiteSparse code (which doesn't have single precision), and that in fact matlab internally uses four calls to DGEMM on the real and imaginary parts of the matrix to simulate ZGEMM as that means that they never explicitly have to form the complex matrix. Given the speed differences (or lack thereof) for such operations between Octave and Matlab I believe that pretty much confirms what they do.
Regards David -- David Bateman address@hiddenMotorola Labs - Paris +33 1 69 35 48 04 (Ph) Parc Les Algorithmes, Commune de St Aubin +33 6 72 01 06 33 (Mob) 91193 Gif-Sur-Yvette FRANCE +33 1 69 35 77 01 (Fax) The information contained in this communication has been classified as: [x] General Business Information [ ] Motorola Internal Use Only [ ] Motorola Confidential Proprietary
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