Thank you, Wolfgang. The explanation was clear as usual, I understood the
principle but overlooked the DoFTools class. This is now set.
Unfortunately, it seems that it does not solve my issue and I guess I
figured out why.
In brief, I am building an
interface matrix and an interface rhs in the very same way cell matrix and
cell rhs have been built in step 18 - as depicted already (I won't repeat
it here).
Issues arise when I attempt at distributing the matrices into system
matrix: I coded this
local_interface_dof_indices = fiv.get_interface_dof_indices() ;
this->hanging_node_constraints.distribute_local_to_global(interface_matrix,
interface_rhs, local_interface_dof_indices, this->system_matrix,
this->system_rhs);
using the very same hanging_node_constraints I used for the usual continuum
elements.
This last statement causes an error FOR TRILINOS (AND NOT FOR PETSc, which
works OK).
According to your remark "make_flux_sparsity_pattern() also adds entries
for DoFs i,j that are located
on cells that are face neighbors of each other" the error may arise because
in defining the interfaces I am:
1 - duplicating the nodes in order to separate the initial triangulation
into two
2 - building a new data structure that provide connectivity for the dofs of
the separated elements, exploiting the class FEInterfaceValues
I wonder if by doing so, the notion of "cells that are face neighbors of
each other" may not apply anymore and hence, as you suspected, I am
computing terms for the interface matrix
that are not part of the sparsity pattern of the Trilinos matrix.
If this is correct, do you see a way to circumvent the TRILINOS problem I
am facing?
Thank you,
Alberto
*Alberto Salvadori* Dipartimento di Ingegneria Meccanica e Industriale
(DIMI)
Universita` di Brescia, via Branze 43, 25123 Brescia
Italy
tel 030 3715426
e-mail:
alberto.salvad...@unibs.it
web-page:
http://m4lab.unibs.it/faculty.html
On Fri, Jan 8, 2021 at 9:10 PM Wolfgang Bangerth <bange...@colostate.edu>
wrote:
> On 1/8/21 10:19 AM, Alberto Salvadori wrote:
> >
> > thank you for the hint. I looked at setp 47 sparsity pattern. If I
> understood
> > it right,
> > the main difference stands in the locally_relevant_dofs, which are no
> longer
> > extracted and used.
> > Rather, the sparsity pattern is based on the whole dof_handler, as per
> the
> > instruction
> >
> > DoFTools::make_flux_sparsity_pattern( this->dof_handler, dsp,
> > this->hanging_node_constraints, true );
>
> No, you mistook what the difference is. The difference is that
> make_sparsity_pattern() only adds entries for the matrix that correspond
> to
> DoFs i and j that are located on the same cell.
>
> make_flux_sparsity_pattern() also adds entries for DoFs i,j that are
> located
> on cells that are face neighbors of each other.
>
> In both cases, you can use the same locally_relevant_set when you set up
> the
> sparsity pattern object.
>
> Best
> W.
>
>
> --
> ------------------------------------------------------------------------
> Wolfgang Bangerth email: bange...@colostate.edu
> www: http://www.math.colostate.edu/~bangerth/
>
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