MatMatMatMult#

Performs matrix-matrix-matrix multiplication D=ABC.

Synopsis#

#include "petscmat.h" 
PetscErrorCode MatMatMatMult(Mat A, Mat B, Mat C, MatReuse scall, PetscReal fill, Mat *D)

Neighbor-wise Collective

Input Parameters#

  • A - the left matrix

  • B - the middle matrix

  • C - the right matrix

  • scall - either MAT_INITIAL_MATRIX or MAT_REUSE_MATRIX

  • fill - expected fill as ratio of nnz(D)/(nnz(A) + nnz(B)+nnz(C)), use PETSC_DEFAULT if you do not have a good estimate if the result is a dense matrix this is irrelevant

Output Parameter#

  • D - the product matrix

Notes#

Unless scall is MAT_REUSE_MATRIX D will be created.

MAT_REUSE_MATRIX can only be used if the matrices A, B and C have the same nonzero pattern as in the previous call

This routine is shorthand for using MatProductCreate() with the MatProductType of MATPRODUCT_ABC

To determine the correct fill value, run with -info and search for the string “Fill ratio” to see the value actually needed.

If you have many matrices with the same non-zero structure to multiply, you should use MAT_REUSE_MATRIX in all calls but the first

See Also#

Matrices, Mat, MatProductCreate(), MATPRODUCT_ABC, MatMatMult, MatPtAP(), MatMatTransposeMult(), MatTransposeMatMult()

Level#

intermediate

Location#

src/mat/interface/matrix.c

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