On 30/11/15 16:14, Eric Chamberland wrote: > Hi, > > Using PETSc 3.5.3. > > We have a "A" matrix, mpi_aij with block_size=3. > > We create a IS with ISCreateStride, then extract A_00 with > MatGetSubMatrix(..., MAT_INITIAL_MATRIX,...). > > We know that A_00 is block_size = 3 and mpi_aij, however the matrix > created by PETSc doesn't have the information... > > How can I have the block_size=3 option into the extracted matrix so the > further PC we configure (gamg) can work with it? > > I tried: > > MatSetBlockSizes(A_00,3, 3); > after the MatGetSubMatrix, but it doesn't change it...
The block size of the submatrix comes from the block size that lives on the IS used to define it. So set a block size on the IS you make (ISSetBlockSize). Cheers, LAwrence
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