[petsc-users] alternative for MatCreateSeqAIJWithArrays

[Qiyue Lu]

Hello,
I am trying to incorporate PETSc as a linear solver to compute Ax=b in my
code. Currently, the sequential version works.
1) I have the global matrix A in CSR format and they are stored in three
1-dimensional arrays: row_ptr[ ], col_idx[ ], values[ ], and I am using
MatCreateSeqAIJWithArrays to get the PETSc format matrix. This works.
2) I am trying to use multicores, and when I use "srun -n 6", I got the
error *Comm must be of size 1* from the MatCreateSeqAIJWithArrays. Saying I
cannot use SEQ function in a parallel context.
3) I don't think MatCreateMPIAIJWithArrays and MatMPIAIJSetPreallocationCSR
are good options for me, since I already have the global matrix as a whole.

I wonder, from the global CSR format data, how can I reach the PETSc format
matrix for parallel KSP computation. Are the MatSetValue, MatSetValues what
I need?

Thanks,
Qiyue Lu
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