Using of MatGetSubMatrices

[Christian Henke]

Thanks!

Now it works.

Christian

Am Montag, 28. August 2006 18:41 schrieb Barry Smith:
>    All processes that share the matrix must call MatGetSubMatrices()
> the same number of times. If a process doesn't need a matrix it should
> pass in zero length IS's. If you are always calling it with all processes
> then you can run with -start_in_debugger and when it is hanging hit
> control C in the debugger and type where to see where/why it is hanging.
>
>   Barry
>
> On Mon, 28 Aug 2006, Christian Henke wrote:
> > Hi all,
> >
> > I am trying with petsc2.2.0 to get access to my sparse
> > blockdiagonalmatrix matrix which contains for example 4 blocks m1 ... m4.
> > If I use 2 Processors then m1 and m2 are owned by p1 and m3, m4 owned by
> > p2. Now I want to read m1, m2 from p2 and m3, m4 from p1. First I have
> > used MatGetValues, but then I took the message: Only local values
> > currently supported.
> > My next try was the function MatGetSubMatrices:
> >
> >     IS             isrow, iscol;
> >     Mat            *M;
> >
> >     ISCreateStride(PETSC_COMM_SELF,m,(int)i*m,1,&isrow);
> >     ISCreateStride(PETSC_COMM_SELF,m,(int)j*m,1,&iscol);
> >
> >     const int ierr
> >       = MatGetSubMatrices(matrix,1,&isrow,&iscol,MAT_INITIAL_MATRIX,&M);
> >
> >     ...
> >
> >     ISDestroy(isrow);
> >     ISDestroy(iscol);
> >
> > where i,j the blockindices and m is the blocksize. It works well for a
> > few functioncalls, but then it stops with the log_trace-message:
> >
> > [0] 0.055568 Event begin: MatGetSubMatrice.
> >
> > What is my error? Is MatGetSubMatrices the wrong function for my problem
> > or are the above lines wrong?
> >
> > Regards Christian

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