petsc-3.12.1 2019-10-22
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# PCApplyBAorAB

Applies the preconditioner and operator to a vector. y = B*A*x or y = A*B*x.

### Synopsis

    #include "petscksp.h"
    PetscErrorCode  PCApplyBAorAB(PC pc,PCSide side,Vec x,Vec y,Vec work)

Collective on PC

### Input Parameters

| pc | - the preconditioner context
| side | - indicates the preconditioner side, one of PC_LEFT, PC_RIGHT, or PC_SYMMETRIC
| x | - input vector
| work | - work vector

### Output Parameter

y -output vector

### Notes

If the PC has had PCSetDiagonalScale() set then D M A D^{-1} for left preconditioning or D A M D^{-1} is actually applied. Note that the specific KSPSolve() method must also be written to handle the post-solve "correction" for the diagonal scaling.

### See Also

PCApply(), PCApplyTranspose(), PCApplyBAorABTranspose()

### Level

developer

### Location

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