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().

An alternative approach to this function is to use MatProductCreate() and set the desired options before the computation is done

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, parallel MatRARt() is implemented via explicit transpose of R, which could be very expensive. We recommend using MatPtAP().

The deprecated PETSC_DEFAULT in fill also means use the current value

Level#

intermediate

Location#

src/mat/interface/matrix.c

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