[row/column majority] gslclapack

Z F mail4me9999@yahoo.com
Thu Mar 30 16:44:00 GMT 2006


Row/column majority question comes from the times when
God was REAL and Infinity was INTEGER (FORTRAN). But even
at that time, some people, I hope, knew that the question of 
row/column majority is irrelevant. Think about it!

So think.... Sorry, but I will use capital letters...

COLUMN-MAJOR or ROW-MAJOR ??? IT IS ALL IN YOUR HEAD!!!!
IT IS NOT REAL AND DOES NOT EXIST!!! THE MATRIX IS STORED
AS A CONTINUOUS OBJECT AND ADDRESSING IS DONE VIA a FORUMLA
LIKE THIS

index = j*Ni+i!!!

SO GIVE THE MAJORITY A REST!!!

Once again, sorry if I offended anyone, but someone had to point it
out.


Lazar

--- James Bergstra <james.bergstra@umontreal.ca> wrote:

> On Wed, Mar 29, 2006 at 07:04:39PM +0100, J.J.Green wrote:
> > I think the problem with calling fortran from C is that
> > it is compiler, OS and (I think) architecture dependant.
> > CLAPACK solves the portability problem, but as you have
> > noticed, not the arcane interface which puts most poeple
> > off using it.
> 
> Exactly the motivation for a gsl wrapper (or extension)!  A
> gsl module would serve both as a gentle introduction to
> using lapack, as well as a hook to place normal
> documentation.
> 
> It seems to me that the largest barrier to a lapack wrapper
> is that gsl_matrix is an implicitly row-major structure, so
> that in general, arguments must be out-of-place transposed
> before a lapack call.  Although this is not significant in
> terms of either O(n) time or space,  the overhead is more
> noticeable in the case of large numbers of calls with small
> arguments.
> 
> Anyway, it seems like the concensus is that lapack is
> annoying to use but good in theory, once it's working.  If
> someone (eg. me) writes an extension that makes (at least
> part of lapack) less annoying to use in practice, share with
> the list?
> 
> 
> James
> 
> PS.  My extension would probably introduce a column-major
> version of gsl_matrix.
> 
> -- 
> james bergstra
> http://www-etud.iro.umontreal.ca/~bergstrj
> 
> 


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