LAPACK performance (was: Definitions of LAPACK)

Hi,

I was talking about the same matrix (same maxima program) that was run
on the same maxima version (5.12 and 5.11.99rc3 are only renamed as far
as I know) but with different lisp versions (gcl, sbcl).

My matrix is not dense, in fact it is close to be diagonal.

Were your measured times with gcl lisp?

Did you use the windows version?

To be exact, I use Debian testing with maxima 5.12 from Debian unstable
installed (as 5.12 is not yet in testing). I could send you my maxima
program to check the timing. Maybe it is a gcl on linux topic?! I had
the feeling it may be a memory management problem, as it crashed with
heap overflow at about 400x400 matrix.

Detlef


Am Mittwoch, den 23.05.2007, 01:09 +0900 schrieb Valery Pipin:
> On ??????? 22 ??? 2007, Detlef Schmicker wrote:
> > Hi Raymond,
> >
> > I just got some experience with LAPACK, which I want to share. I used
> > dgeev to get the eigenvalues of a 200x200 Matrix. Using gcl (Debian
> > unstable maxima 5.12) it was impossble to do, as it took a day and
> > crashed. Using sbcl (compiled from 5.11.99rc3) was by a factor of at
> > least 50 faster (Tested with 50x50 Matrix) and it solved the (200x200)
> > eigenvector problems.
> > Just in case, anybody is frustrated with this.
> Depends on matrix perhaps. How did you form the matrix?
> I've made the 2D Galerkin code for eigen value dynamo problem (large-scale 
> magnetic field generation on the Sun and convective stars).
> Matrix 234x234 is solved on 3-4 seconds with dgeev.
> The bifurcation diagram with 25 points is ready within a minute or so.
> Moreover the pure diffusion matrix (though it is not a diagonal one because 
> diffusion is anisotropic and dependent of coordinates) is calculated much 
> faster.
> 
> This is on celeron 1.6Ghz with 512 mb Ram notebook toshiba satelite l-113.
> 
> I would recomend to check the matrix itself to make it better. 
> Note, if I would solve the same task with pseudospectral approach I would have 
> the dense and not well-conditioned matrix and dgeev would work much longer.
> 
> 
> 
> 
>    
> 
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