dolfin team mailing list archive

["Garth N. Wells" <g.n.wells@xxxxxxxxxx>]

Anders Logg wrote:
> On Fri, Apr 27, 2007 at 05:24:34PM +0200, Garth N. Wells wrote:
> > Anders Logg wrote:
> > > I'm comparing the entries in the Stokes systems between the new code
> > > and the old and there seem to be quite a few more zeros in the sparse
> > > matrix than before.
> > Strange. Have you counted the non-zeroes, or are you displaying the matrix?
>
> Displaying the matrix and counting everything that looks like zero.
> (Just looking at the numbers.)

There are about double the number of non-zeros (you can get the number 
by A.nnz()) for the Stokes example with the new version compared to 
version 0.6.4. For poisson and elasticity, the number of non-zeroes is 
the same as with version 0.6.4. The linear algebra looks fine - 
something is going on with the computation of the sparsity pattern for 
the Stokes problem.

Garth


> /Anders
>
>
> > Garth
> >
> > > Could this have anything to do with the initialization of uBlas
> > > matrices with a sparsity pattern and not using the temporary storage
> > > as before? Did we have a check that removed zeros?
> > >
> > > I haven't tried with PETSc.
> > >
> > > /Anders
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