PETSc version 3.16.5
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# KSPBuildResidual

Builds the residual in a vector provided.

### Synopsis

    #include "petscksp.h"
    #include "petscmat.h"
    PetscErrorCode  KSPBuildResidual(KSP ksp,Vec t,Vec v,Vec *V)

Collective on ksp

### Input Parameter

| ksp | - iterative context obtained from KSPCreate()

### Output Parameters

| v | - optional location to stash residual. If v is not provided, then a location is generated.
| t | - work vector. If not provided then one is generated.
| V | - the residual

### Notes

Regardless of whether or not v is provided, the residual is returned in V.

### See Also

KSPBuildSolution()

### Level

advanced

### Location

src/ksp/ksp/interface/itfunc.c

### Examples

src/ksp/ksp/tutorials/ex42.c.html

### Implementations

KSPBuildResidual_CG in src/ksp/ksp/impls/cg/cg.c
KSPBuildResidual_GCR in src/ksp/ksp/impls/gcr/gcr.c
KSPBuildResidual_Richardson in src/ksp/ksp/impls/rich/rich.c
Index of all KSP routines
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Index of all manual pages