[Numpy-discussion] Numpy, BLAS & LAPACK (original) (raw)

David M. Cooke cookedm at physics.mcmaster.ca
Fri Jun 2 15:56:32 EDT 2006

On Fri, 2 Jun 2006 19:09:01 +0200 Joris De Ridder <joris at ster.kuleuven.be> wrote:

Just to be sure, what exactly is affected when one uses the slower algorithms when neither BLAS or LAPACK is installed? For sure it will affect almost every function in numpy.linalg, as they use LAPACKlite. And I guess that in numpy.core the dot() function uses the lite numpy/core/blasdot/dotblas.c routine? Any other numpy functions that are affected?

Using a better default dgemm for matrix multiplication when an optimized BLAS isn't available has been on my to-do list for a while. I think it can be speed up by a large amount on a generic machine by using blocking of the matrices.

Personally, I perceive no difference between my g77-compiled LAPACK, and the gcc-compiled f2c'd routines in lapack_lite, if an optimized BLAS is used. And lapack_lite has fewer bugs than the version of LAPACK available off of netlib.org, as I used the latest patches I could scrounge up (mostly from Debian).

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