[petsc-users] Coloring of a parallel matrix

Jed Brown jedbrown at mcs.anl.gov
Wed Sep 7 03:00:15 CDT 2011


On Wed, Sep 7, 2011 at 08:59, Kostas Kontzialis <ckontzialis at lycos.com>wrote:

>  I'm using a matrix free method for the solution of the Navier-Stokes
> equaiotns on unstructured meshes. I want to numerically evaluate the
> elements of the residual's Jacobian matrix. I know  where the non zero
> elements of the matrix are, but I read on the manual, that function
> MatGetColoring works only on sequential matrices. What should I do?


It actually works for parallel matrices, but the underlying algorithm is
serial.  You can use it for tests and small problems, but it does not scale.

PETSc does not currently have a parallel graph coloring implementation, so
you would have to compute a coloring yourself if you intend to use this for
larger problem sizes.
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