petsc-3.14.5 2021-03-03
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# PCREDUNDANT

Runs a KSP solver with preconditioner for the entire problem on subgroups of processors Options for the redundant preconditioners can be set with -redundant_pc_xxx for the redundant KSP with -redundant_ksp_xxx

### Options Database

| -pc_redundant_number <n> | - number of redundant solves, for example if you are using 64 MPI processes and use an n of 4 there will be 4 parallel solves each on 16 = 64/4 processes.

### Notes

The default KSP is preonly and the default PC is LU or CHOLESKY if Pmat is of type MATSBAIJ.

PCFactorSetShiftType() applied to this PC will convey they shift type into the inner PC if it is factorization based.

### Developer Notes

Note that PCSetInitialGuessNonzero() is not used by this class but likely should be.

### See Also

PCCreate(), PCSetType(), PCType (for list of available types), PCRedundantSetScatter(),
PCRedundantGetKSP(), PCRedundantGetOperators(), PCRedundantSetNumber()

### Level

intermediate

### Location

src/ksp/pc/impls/redundant/redundant.c
Index of all PC routines
Table of Contents for all manual pages
Index of all manual pages