On 02/18/2013 05:28 PM, Dag Sverre Seljebotn wrote: > On 02/18/2013 05:26 PM, rif wrote: >> I have no answer to the question, but I was curious as to why directly >> calling the cblas would be 10x-20x slower in The statement was that directly (on the Cython level) calling cblas is 10x-20x slower than going through the (slow) SciPy wrapper routines. That makes a lot of sense if the matrices are smalle nough. the first place. That >> seems surprising, although I'm just learning about python numerics. > > The statement was that directly (on the Cython level) calling cblas is > 10x-20x slower than going through the (slow) SciPy wrapper routines. > That makes a lot of sense if the matrices are smalle nough. >
Argh. I meant: The statement was that directly (on the Cython level) calling cblas is 10x-20x **faster** than going through the (slow) SciPy wrapper routines. That makes a lot of sense if the matrices are small enough. Dag Sverre > Dag Sverre > >> >> >> On Mon, Feb 18, 2013 at 7:38 AM, Sergio Callegari >> <sergio.calleg...@gmail.com <mailto:sergio.calleg...@gmail.com>> wrote: >> >> Hi, >> >> I have a project that includes a cython script which in turn does >> some direct >> access to a couple of cblas functions. This is necessary, since some >> matrix >> multiplications need to be done inside a tight loop that gets called >> thousands >> of times. Speedup wrt calling scipy.linalg.blas.cblas routines is >> 10x to 20x. >> >> Now, all this is very nice on linux where the setup script can >> assure that the >> cython code gets linked with the atlas dynamic library, which is the >> same >> library that numpy and scipy link to on this platform. >> >> However, I now have trouble in providing easy ways to use my >> project in >> windows. All the free windows distros for scientific python that I >> have >> looked at (python(x,y) and winpython) seem to repackage the windows >> version of >> numpy/scipy as it is built in the numpy/scipy development sites. >> These appear >> to statically link atlas inside some pyd files. So I get no atlas >> to link >> against, and I have to ship an additional pre-built atlas with my >> project. >> >> All this seems somehow inconvenient. >> >> In the end, when my code runs, due to static linking I get 3 >> replicas of 2 >> slightly different atlas libs in memory. One coming with >> _dotblas.pyd in numpy, >> another one with cblas.pyd or fblas.pyd in scipy. And the last one >> as the one >> shipped in my code. >> >> Would it be possible to have a win distro of scipy which provides >> some >> pre built atlas dlls, and to have numpy and scipy dynamically link >> to them? >> This would save memory and also provide a decent blas to link to for >> things >> done in cython. But I believe there must be some problem since the >> scipy site >> says >> >> "IMPORTANT: NumPy and SciPy in Windows can currently only make use >> of CBLAS and >> LAPACK as static libraries - DLLs are not supported." >> >> Can someone please explain why or link to an explanation? >> >> Unfortunately, not having a good, prebuilt and cheap blas >> implementation in >> windows is really striking me as a severe limitation, since you >> loose the >> ability to prototype in python/scipy and then move to C or Cython >> the major >> bottlenecks to achieve speed. >> >> Many thanks in advance! >> >> _______________________________________________ >> NumPy-Discussion mailing list >> NumPy-Discussion@scipy.org <mailto:NumPy-Discussion@scipy.org> >> http://mail.scipy.org/mailman/listinfo/numpy-discussion >> >> >> >> >> _______________________________________________ >> NumPy-Discussion mailing list >> NumPy-Discussion@scipy.org >> http://mail.scipy.org/mailman/listinfo/numpy-discussion >> > _______________________________________________ NumPy-Discussion mailing list NumPy-Discussion@scipy.org http://mail.scipy.org/mailman/listinfo/numpy-discussion
