MatPtAP#

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

Synopsis#

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

Neighbor-wise Collective

Input Parameters#

  • A - the matrix

  • P - the projection matrix

  • scall - either MAT_INITIAL_MATRIX or MAT_REUSE_MATRIX

  • fill - expected fill as ratio of nnz(C)/(nnz(A) + nnz(P)), use PETSC_DEFAULT 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

Developer Note#

For matrix types without special implementation the function fallbacks to MatMatMult() followed by MatTransposeMatMult().

See Also#

Matrices, Mat, MatProductCreate(), MatMatMult(), MatRARt()

Level#

intermediate

Location#

src/mat/interface/matrix.c

Examples#

src/ksp/ksp/tutorials/ex76.c
src/tao/pde_constrained/tutorials/elliptic.c

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Index of all manual pages