[petsc-users] Two Questions about Matrix Preallocation

[behzad baghapour]

Dear Developers,

I am facing with two questions about Block-Sparse Preallocation:

1- I set array "nnz[]" and did:

    MatSetType ( JAC, MATSEQBAIJ );
    MatSetSizes( JAC, PETSC_DECIDE, PETSC_DECIDE, nt, nt );
    MatSeqAIJSetPreallocation( JAC, 0, nnz );

but when I saw log file with -info -mat_view_info, I found this message:

[0] MatSetUpPreallocation(): Warning not preallocating matrix storage

What this means? Did I correctly preallocate the matrix?

2- I need to test MatSeqBAIJSetPreallocation() too but I little confused
with descriptions of the command in man-page:

what are "nz" and "nnz[]" in this case?

what about number of blocks per row?

Thanks bothering too much :-)
BehZad
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