KSPSetUseExplicitTranspose

Determines whether the explicit transpose of the operator is formed in KSPSolveTranspose() and KSPMatSolveTranspose()

Synopsis

#include "petscksp.h" 
#include "petscmat.h" 
PetscErrorCode KSPSetUseExplicitTranspose(KSP ksp, PetscBool flg)

Collective

Input Parameters

• ksp - the KSP context

• flg - PETSC_TRUE to transpose the system explicitly, PETSC_FALSE to not transpose explicitly (default)

Options Database Key

• -ksp_use_explicittranspose - transpose the system explicitly in KSPSolveTranspose() and KSPMatSolveTranspose()

Note

Explicitly forming the transpose may improve solve performance in some configurations, such as on GPUs. When enabled, the explicitly transposed operators replace the KSP operators and remain set after KSPSolveTranspose() or KSPMatSolveTranspose(), so KSPGetOperators() returns the transposed operators. A subsequent non-transpose KSPSolve() or KSPMatSolve(), or disabling this option, restores any cached transposed operator that is still set to its parent operator. Alternating between transpose and non-transpose solves requires the preconditioner to be set up again on every direction change; use separate KSP objects when both directions are solved repeatedly.

See Also

KSP: Linear System Solvers, KSPSolveTranspose(), KSPMatSolveTranspose(), KSPSetOperators(), KSPGetOperators(), KSP

Level

advanced

Location

src/ksp/ksp/interface/itfunc.c

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Index of all KSP routines
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