MatPtAP#
Creates the matrix product \(C = P^T * A * P\)
Synopsis#
Neighbor-wise Collective
Input Parameters#
A - the matrix
P - the projection matrix
scall - either
MAT_INITIAL_MATRIXorMAT_REUSE_MATRIXfill - expected fill as ratio of nnz(C)/(nnz(A) + nnz(P)), use
PETSC_DETERMINEorPETSC_CURRENTif 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
The deprecated PETSC_DEFAULT in fill also means use the current value
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#
Examples#
src/tao/pde_constrained/tutorials/elliptic.c
src/ksp/ksp/tutorials/ex76.c
Index of all Mat routines
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Index of all manual pages