MatRARt#

Creates the matrix product \(C = R * A * R^T\)

Synopsis#

#include "petscmat.h" 
PetscErrorCode MatRARt(Mat A, Mat R, MatReuse scall, PetscReal fill, Mat *C)

Neighbor-wise Collective

Input Parameters#

A - the matrix
R - the projection matrix
scall - either MAT_INITIAL_MATRIX or MAT_REUSE_MATRIX
fill - expected fill as ratio of nnz(C)/nnz(A), use PETSC_DETERMINE or PETSC_CURRENT if you do not have a good estimate if the result is a dense matrix this is irrelevant

Output Parameter#

C - the product matrix

Notes#

C will be created and must be destroyed by the user with MatDestroy().

This is a convenience routine that wraps the use of the MatProductCreate() with a MatProductType of MATPRODUCT_RARt functionality into a single function call. For more involved matrix-matrix operations see MatProductCreate().

This routine is currently only implemented for pairs of MATAIJ matrices and classes which inherit from MATAIJ. Due to PETSc sparse matrix block row distribution among processes, the parallel MatRARt() is implemented computing the explicit transpose of R, which can be very expensive. We recommend using MatPtAP() when possible.

The deprecated PETSC_DEFAULT in fill also means use the current value

Level#

intermediate

Location#

src/mat/interface/matrix.c

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