[petsc-dev] MatSetValuesBlocked not inserting values

[Jed Brown]

What are idxm[0] and idxn[0] in this code?

Jacob Faibussowitsch <jacob.fai at gmail.com> writes:

> Hello All,
>
> I am using MATSBAIJ to make a symmetric hamiltonian matrix, but for some reason MatSetValuesBlocked isn’t inserting anything. 
>
> Setup:
>
> I want a 4n x 4n symmetric matrix, where each MatSetValuesBlocked inserts a 4x4 sub-matrix of values into the global matrix, positioned by the global ID of two atoms that I am extracting. So the 4x4 interaction sub matrix between atom 1 and atom 4 will be in rows 0-4 and cols 16-20.
>
> My non-working implementation:
>
> PetscInt bs = 4;
>
> ierr = MatCreateSBAIJ(comm, bs, bs*nLocalAtoms, bs*nLocalAtoms, PETSC_DETERMINE, PETSC_DETERMINE, 1, NULL, 1, NULL, H);CHKERRQ(ierr);
> ierr = MatSetOption(*H, MAT_SYMMETRIC, PETSC_TRUE);CHKERRQ(ierr);
> ierr = MatSetUp(*H);CHKERRQ(ierr);                                    
> .
> .
> .
> START LOOP {
>
> Calculations...
>
> const PetscScalar  valmat[16] = {Es[0], Es[1], Es[2], Es[3], Ex[0], Ex[1], Ex[2], Ex[3], Ey[0], Ey[1], Ey[2], Ey[3], Ez[0], Ez[1], Ez[2], Ez[3]};
> PetscInt                  idxm[1], idxn[1];
> PetscInt                  m = 1, n = 1;
>
> if (globalIDs[i] < globalIDs[neighidx[0]]-1) {
> 	// Insert in upper triangular
>         idxm[0] = globalIDs[i]-1;
>         idxn[0] = globalIDs[neighidx[0]]-1;
> } else {
>         // swap so we insert on upper triangular                                                    
>         idxn[0] = globalIDs[i]-1;
>         idxm[0] = globalIDs[neighidx[0]]-1;
> }
> ierr = MatSetValuesBlocked(*H, m, (const PetscInt *) idxm, n, (const PetscInt *) idxn, valmat, INSERT_VALUES);CHKERRQ(ierr);
> } END LOOP
>
> ierr = MatAssemblyBegin(*H, MAT_FINAL_ASSEMBLY);CHKERRQ(ierr);
> ierr = MatAssemblyEnd(*H, MAT_FINAL_ASSEMBLY);CHKERRQ(ierr);
>
> RETURN H
>
> Output from -mat_view:
>
> Mat Object: 2 MPI processes
>   type: mpisbaij
> row 0:
> row 1:
> row 2:
> row 3:
> row 4:
> row 5:
> row 6:
> row 7:
> row 8:
> row 9:
> row 10:
> row 11:
> row 12:
> row 13:
> row 14:
> row 15:
>
> I also checked -info :mat: and it also reports X unneeded storage space but more importantly, 0 used. I am not sure what is going wrong here. 
>
> Best regards,
>
> Jacob Faibussowitsch
> (Jacob Fai - booss - oh - vitch)
> Cell: (312) 694-3391