[CP2K:3992] creating a sparse dbcsr matrix

Adam aml... at ucdavis.edu
Tue Aug 28 22:35:39 CEST 2012


Thanks! Our matrices fit on one computer so the filter works for showing 
linear scaling for now.

-Adam

On Monday, August 27, 2012 2:35:28 AM UTC-6, Urban wrote:
>
> Hi Adam, 
>
> On Fri, 2012-08-24 at 16:34 -0700, Adam wrote: 
> > Hi, 
> > 
> > 
> > I'm creating dbcsr matrices out of dense 2d fortran arrays. However 
> > few elements are non-zero values, and I'd like to build a dbcsr matrix 
> > in sparse format so I can see speed ups when doing multiplication. The 
> > examples provided with the dbcsr package only show how to build dense 
> > random matrices. Is there any examples on building sparse matrices, or 
> > can you tell me how a sparse matrix is built? Right now timing my code 
> > it is scaling closer to order n^3 than n. Any help is much 
> > appreciated. 
>
> There are generally two basic approaches to having a sparse matrix: 
> either you know the sparsity pattern beforehand and store only the 
> appropriate blocks in the matrix or you completely fill the matrix and 
> then filter it (using the dbcsr_filter* subroutine(s)).  The latter is 
> easier to do but it's really only a hack.  It only works in cases where 
> dense the matrix fits in memory; however, since it's still distributed, 
> it's usually not a show-stopper. 
>
> Regards, 
> Urban. 
>
> > 
> > Thanks, 
> > Adam 
> > 
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