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_DETERMINE or PETSC_CURRENT 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

The deprecated PETSC_DEFAULT in fill also means use the current value

See Also

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

Level

intermediate

Location

src/mat/interface/matrix.c

Examples

src/ksp/pc/tutorials/ex4.c

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Index of all Mat routines
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Index of all manual pages