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# KSPFBCGS

Implements the flexible BiCGStab method. Flexible Krylov Methods

## Notes

Flexible BiCGStab, unlike most Krylov methods, allows the preconditioner to be nonlinear, that is the action of the preconditioner to a vector need not be linear in the vector entries.

`KSPFBCGSR` provides another variant of this algorithm that requires fewer `MPI_Allreduce()` calls and my converge faster

See `KSPPIPEBCGS` for a pipelined version of the algorithm

Only supportst right preconditioning

## See Also

KSP: Linear System Solvers, Flexible Krylov Methods, `KSPFBCGSR`, `KSPPIPEBCGS`, `KSPBCGSL`, `KSPFBCGS`, `KSPCreate()`, `KSPFGMRES`, `KSPSetType()`, `KSPType`, `KSP`, `KSPBICG`, `KSPSetPCSide()`

## Level

beginner

## Location

src/ksp/ksp/impls/bcgs/fbcgs/fbcgs.c

Index of all KSP routines
Table of Contents for all manual pages
Index of all manual pages