Returns a matrix suitable to calls to MatXXFactorSymbolic,Numeric()


#include "petscmat.h" 
PetscErrorCode MatGetFactor(Mat mat, MatSolverType type, MatFactorType ftype, Mat *f)


Input Parameters#

Output Parameter#

  • f - the factor matrix used with MatXXFactorSymbolic,Numeric() calls. Can be NULL in some cases, see notes below.

Options Database Keys#

  • -pc_factor_mat_solver_type - choose the type at run time. When using KSP solvers

  • -mat_factor_bind_factorization <host, device> - Where to do matrix factorization? Default is device (might consume more device memory. One can choose host to save device memory). Currently only supported with MATSEQAIJCUSPARSE matrices.


The return matrix can be NULL if the requested factorization is not available, since some combinations of matrix types and factorization types registered with MatSolverTypeRegister() cannot be fully tested if not at runtime.

Users usually access the factorization solvers via KSP

Some PETSc matrix formats have alternative solvers available that are contained in alternative packages such as pastix, superlu, mumps etc. PETSc must have been ./configure to use the external solver, using the option –download-package or –with-package-dir

When type is NULL the available results are searched for based on the order of the calls to MatSolverTypeRegister() in MatInitializePackage(). Since different PETSc configurations may have different external solvers, seemingly identical runs with different PETSc configurations may use a different solver. For example if one configuration had –download-mumps while a different one had –download-superlu_dist.

Some of the packages have options for controlling the factorization, these are in the form -prefix_mat_packagename_packageoption where prefix is normally obtained from the calling KSP/PC. If MatGetFactor() is called directly one can set call MatSetOptionsPrefixFactor() on the originating matrix or MatSetOptionsPrefix() on the resulting factor matrix.

Developer Note#

This should actually be called MatCreateFactor() since it creates a new factor object

See Also#

Matrices, Mat, Matrix Factorization, KSP, MatSolverType, MatFactorType, MatCopy(), MatDuplicate(), MatGetFactorAvailable(), MatFactorGetCanUseOrdering(), MatSolverTypeRegister(), MatSolverTypeGet() MAT_FACTOR_LU, MAT_FACTOR_CHOLESKY, MAT_FACTOR_ICC, MAT_FACTOR_ILU, MAT_FACTOR_QR, MatInitializePackage()






MatGetFactor_HT() in src/mat/impls/transpose/htransm.c
MatGetFactor_Transpose() in src/mat/impls/transpose/transm.c

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