PCBDDCSetLocalAdjacencyGraph#

Sets the adjacency graph of the local degrees of freedom in CSR format

Synopsis#

#include "petscpc.h" 
PetscErrorCode PCBDDCSetLocalAdjacencyGraph(PC pc, PetscInt nvtxs, const PetscInt xadj[], const PetscInt adjncy[], PetscCopyMode copymode)

Not Collective

Input Parameters#

pc - the preconditioning context
nvtxs - number of local graph vertices, equal to the number of local degrees of freedom
xadj - CSR row offsets, of length nvtxs + 1
adjncy - CSR column indices, of length xadj[nvtxs]
copymode - PETSC_COPY_VALUES, PETSC_USE_POINTER, or PETSC_OWN_POINTER

Notes#

Graph vertices use the numbering of the local MATIS matrix. The CSR arrays use zero-based indexing. A degree of freedom i is considered connected to all local degrees of freedom if xadj[i+1] - xadj[i] == 1 and adjncy[xadj[i]] is negative.

With PETSC_COPY_VALUES, the arrays are copied. With PETSC_OWN_POINTER, ownership of the arrays is transferred to pc; the arrays must have been allocated with PetscMalloc(). With PETSC_USE_POINTER, the caller must keep the arrays valid and unchanged until the graph is replaced or the preconditioner is reset or destroyed.

Passing nvtxs equal to 0 clears the user-defined graph.