Re: Who uses clapack?
From: Victor Eijkhout (see.sig_at_for.addy)
Date: 12/10/04
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Date: Fri, 10 Dec 2004 13:27:49 -0500
Dan Pop <Dan.Pop@cern.ch> wrote:
> The issue that springs to mind is that Fortran and C store matrices
> differently: Fortran does it column-wise (the first index varies fastest),
> C does it row-wise (the last index varies fastest).
>
> The fact that Fortran array indexing is 1-based (by default) and C array
> indexing is 0-based shouldn't cause any problems when using the compiled
> Fortran code from C.
These sort of issues make me wonder why clapack is considered so great:
it does not provide arrays in the C-natural order, and in some places
the 1-based indexing is exposed, such as in pivoting of the
factorization.
When we write a more C-native interface we'll try to cover these issues.
It will mean some minimal bit of glue code that will hardly impact
performance.
Thanks for your response.
V.
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