Parallel partitioning of the matrix

[Nguyen, Hung V ERDC-ITL-MS]

All,

I have a test case that each processor reads its owned part of matrix in csr
format dumped out by CFD application.
Note: the partitions of matrix were done by ParMetis.   
 
Code below shows how to insert data into PETSc matrix (gmap is globalmap).
The solution from PETSc is very closed to CFD solution so I think it is
correct.
   
My question is whether the parallel partitioning of the matrix is determined
by PETSc at runtime or is the same as ParMetis?

Thank you,

-hung
---
      /* create a matrix object */
        MatCreateMPIAIJ(PETSC_COMM_WORLD, my_own, my_own,M,M, mnnz,
                   PETSC_NULL, mnnz, PETSC_NULL, &A);

      for(i =0; i < my_own; i++) {
           int row = gmap[i];
           for (j = ia[i]; j < ia[i+1]; j++) {
             int col = ja[j]; 
             jj = gmap[col];
             MatSetValues(A,1,&row,1,&jj,&val[j], INSERT_VALUES);
         }
       }
/* free temporary arrays */
       free(val); free(ja); free(ia);

/* assemble the matrix and vectors*/
      MatAssemblyBegin(A, MAT_FINAL_ASSEMBLY);
      MatAssemblyEnd(A, MAT_FINAL_ASSEMBLY);