Reading a Sparse matrix in CRS format from a function to be used in parallel linear solvers

[Hong Zhang]

Dominic,

You may use MatCreateMPIIJWithArrays() to achieve this.

Hong

On Wed, 31 Jan 2007, Matthew Knepley wrote:

> On 1/31/07, #DOMINIC DENVER JOHN CHANDAR# <DOMI0002 at ntu.edu.sg> wrote:
> >
> >  Hi,
> >
> >        I have a function which creates a sparse matrix following a certain
> > eqn and returns a pointer to the row, column index and the value of a sparse
> > matrix (CRS- form).
> > i   j   val
> > 1  1  1.0
> > 2  2  1.0
> > 2  3  -1.5..
> > so on...
> >
> >  The matrix *may not **have a definite pattern* like the one we see for
> > tridiagonal or pentadiagonal matrices or the test cases (linear solvers)
> > cited in the petsc documentation. Now, i would like to use the linear
> > solvers in petsc to solve the system of equations. I do not want to write
> > that sparse matrix into a file and read it into petsc since it may be
> > huge.I would like to call that function from petsc and would return the
> > pointer to i j and val and insert values of this sparse matrix using
> > MatSetValues in parallel. How can I achieve this ?
> >
>
> We do not have CRS format as it is not a very space efficient format. Most
> of our formats are row-oriented. I suggest
> looking at the example for MatSetValues() and trying to rework the
> discretization function to directly call this. Most
> discretizations naturally generate row-by-row values or even blocks like
> FEM. Even totally nustructured stuff from
> economics is row-by-row.
>
>   Thanks,
>
>     Matt
>
> Cheers,
> > Dominic
> >
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