PCFactorSetUseInPlace#

Tells the system to do an in-place factorization. For dense matrices, this enables the solution of much larger problems. For sparse matrices the factorization cannot be done truly in-place so this does not save memory during the factorization, but after the matrix is factored, the original unfactored matrix is freed, thus recovering that space. For ICC(0) and ILU(0) with the default natural ordering the factorization is done efficiently in-place.

Synopsis#

#include "petscpc.h" 
PetscErrorCode PCFactorSetUseInPlace(PC pc, PetscBool flg)

Logically Collective

Input Parameters#

pc - the preconditioner context
flg - PETSC_TRUE to enable, PETSC_FALSE to disable

Options Database Key#

-pc_factor_in_place <true,false>- Activate/deactivate in-place factorization

Note#

PCFactorSetUseInplace() can only be used with the KSP method KSPPREONLY or when a different matrix is provided for the multiply and the preconditioner in a call to KSPSetOperators(). This is because the Krylov space methods require an application of the matrix multiplication, which is not possible here because the matrix has been factored in-place, replacing the original matrix.