[petsc-users] Question regarding

[Aldo Bonfiglioli]

Hi there,

I am (successfully) using the following piece of code to insert 
elemental matrices into the "global" matrix "jac":

> !
> if( matrix_assembly )then
> !
> i = 0
> PetscCall(DMPlexGetTransitiveClosure(dm, cell, useCone, 
> PETSC_NULL_INTEGER, p_points, ierr))
> !
> !     loop over the vertices of the cell
> !
> do j = vtxbgn, vtxend, 2  ! this is ndim-dependent
>               i = i + 1
>               point = p_points(j)
> PetscCall(PetscSectionGetDof(section, point, ndofs, ierr))
>               PetscCall(PetscSectionGetOffset(section, point, offset, 
> ierr))
>               row(i) = offset/ndofs
>               col(i) = offset/ndofs
>            end do
> !
> do i = 1, nofvert
> do j = 1, nofvert
> dummy = transpose(eltmat(:, :, i, j))
> ir = row(i)
> ic = col(j)
> !
> !p_dummyisa1dviewofdummy
> !
> PetscCall(MatSetValuesBlockedLocal(jac, 2, [ir], 1, [ic], p_dummy, 
> ADD_VALUES, ierr))
> end do
> end do
> !
> PetscCall(DMPlexRestoreTransitiveClosure(dm, cell, useCone, 
> PETSC_NULL_INTEGER, p_points, ierr))
> !
> end if ! matrix_assembly
>
I would however be happy to replace all of the above with a single call to:

> PetscCall(DMPlexMatSetClosure(dm, PETSC_NULL_SECTION, 
> PETSC_NULL_SECTION, jac, cell, values, ADD_VALUES, ierr ))
which I actually succeeded to do as long as ndofs = 1.

The question is:

how (in which order) should I "transfer" the entries of 
eltmat(1:ndofs,1:ndofs,1:nofvert,1:nofvert) into the values array 
required by DMPlexMatSetClosure ?

Thanks,

Aldo

-- 
Dr. Aldo Bonfiglioli
Associate professor of Fluid Mechanics
Dipartimento di Ingegneria
Universita' della Basilicata
V.le dell'Ateneo Lucano, 10 85100 Potenza ITALY
tel:+39.0971.205203 fax:+39.0971.205215
web:https://urldefense.us/v3/__http://docenti.unibas.it/site/home/docente.html?m=002423__;!!G_uCfscf7eWS!ZusjOf_nCidORTOchtNsX_xGJZNjiAXMKKmn4rDhnR-3Y6mFzMF9Z7f7iJFeGj6tgcBzT2L5gtfxO56AMvPr3pgXHaCPziR-QL4$ 
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