[petsc-users] MATMPIBAIJ matrix allocation

[Jose E. Roman]

El 31/07/2013, a las 12:03, Heikki Virtanen escribió:

> Hi, Sorry to bother you, but I still have problems with MATMPIBAIJ matrices. It is said here
> 
> http://www.mcs.anl.gov/petsc/petsc-current/docs/manualpages/Mat/MatCreateBAIJ.html
> 
> that these matrices are created using block compressed row format. It means this one
> 
> http://www.cs.colostate.edu/~mroberts/toolbox/c++/sparseMatrix/sparse_matrix_compression.html
> 
> or something else? (indices start here from 1 not from 0, but if this is fixed, then the format should be the same?)

No, the format explained in that page supports variable block sizes.
In PETSc all blocks have the same dimension (square blocks). The sparsity pattern (rows,cols) refers to blocks, not matrix entries.
See http://www.mcs.anl.gov/petsc/petsc-3.4/docs/manualpages/Mat/MatSetValuesBlocked.html

> I have also second question. What does "block size" mean? Is it number of elements per side of the Block?

Yes.

Jose

> 
> -Heikki