#include "petscmat.h" PetscErrorCode MatMatMult(Mat A,Mat B,MatReuse scall,PetscReal fill,Mat *C)Neighbor-wise Collective on Mat Many br
A | - the left matrix Many br | |
B | - the right matrix Many br | |
scall | - either MAT_INITIAL_MATRIX or MAT_REUSE_MATRIX Many br | |
fill | - expected fill as ratio of nnz(C)/(nnz(A) + nnz(B)), use PETSC_DEFAULT if you do not have a good estimate Many brif the result is a dense matrix this is irrelevent Many br |
MAT_REUSE_MATRIX can only be used if the matrices A and B have the same nonzero pattern as in the previous call Many br
To determine the correct fill value, run with -info and search for the string "Fill ratio" to see the value Many bractually needed. Many br
If you have many matrices with the same non-zero structure to multiply, you Many brshould either Many br
1) use MAT_REUSE_MATRIX in all calls but the first or
2) call MatMatMultSymbolic() once and then MatMatMultNumeric() for each product neededIn the special case where matrix B (and hence C) are dense you can create the correctly sized matrix C yourself and then call this routine Many brwith MAT_REUSE_MATRIX, rather than first having MatMatMult() create it for you. You can NEVER do this if the matrix C is sparse. Many br
Many br
Level:intermediate
Location:src/mat/interface/matrix.c
Index of all Mat routines
Table of Contents for all manual pages
Index of all manual pages