Some questions regarding PETsc

Satish Balay balay at
Sat Dec 23 02:03:01 CST 2006

On Fri, 22 Dec 2006, Matthew Knepley wrote:

> > 1. Is Intel MKL much faster than the downloaded BLAS/LAPACK? Or is it true
> > only for really large problem? Is ATLAS a good alternative too?

> This depends heavily on the architecture and on the BLAS operations
> used. I don't think it much faster, but Satish may know better.

Yeah - MKL will be faster. But I don't think one should worry about it
for noral use. However if you are interested in obtaining the best
performance numbers - perhaps for publishing results - one of the
optimzations could be choosing blas with best performance. [higher
performing compilers is another choice one could make etc..]

> > 2. Can shared library be use in win32? I tried using --with-shared
> > but after ./configure it still reports shared library disabled

> No, we never had the time/manpower to implement the completely
> different Windows paradigm for dynamic libraries.

There is a way to build .dll files with cygwin gcc/g77 - but this
process is not automated [requires a bit of manual tweaking to get
this working].


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