MatSetUnfactored

Resets a factored matrix to be treated as unfactored.

Synopsis

int MatSetUnfactored(Mat mat)
Collective on Mat

Input Parameter

mat -the factored matrix to be reset

Notes

This routine should be used only with factored matrices formed by in- placefactorization via ILU(0) (or by in-place LU factorization for the MATSEQDENSEformat). This option can save memory, for example, when solving nonlinearsystems with a matrix-free Newton-Krylov method and a matrix-based, in- placeILU(0) preconditioner.

Note that one can specify in-place ILU(0) factorization by calling

    PCType(pc,PCILU);
    PCILUSeUseInPlace(pc);
or by using the options -pc_type ilu - pc_ilu_in_place

In-place factorization ILU(0) can also be used as a localsolver for the blocks within the block Jacobi or additive Schwarzmethods (runtime option: -sub_pc_ilu_in_place). See the discussionof these preconditioners in the users manual for details on settinglocal solver options.

See Also

PCILUSetUseInPlace(), PCLUSetUseInPlace()

Keywords

matrix-free, in-place ILU, in-place LU

Location: src/mat/interface/matrix.c
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