:orphan:
# PCApplySymmetricLeft
Applies the left part of a symmetric preconditioner to a vector. 
## Synopsis
```
#include "petscksp.h" 
PetscErrorCode PCApplySymmetricLeft(PC pc, Vec x, Vec y)
```
Collective


## Input Parameters

- ***pc -*** the preconditioner context
- ***x -*** input vector



## Output Parameter

- ***y -*** output vector





## Note
Currently, this routine is implemented only for `PCICC` and `PCJACOBI` preconditioners.


## See Also
 `PC`, `PCApply()`, `PCApplySymmetricRight()`

## Level
developer

## Location
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/ksp/pc/interface/precon.c.html#PCApplySymmetricLeft">src/ksp/pc/interface/precon.c</A>

## Implementations

<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/ksp/pc/impls/factor/cholesky/cholesky.c.html#PCApplySymmetricLeft_Cholesky">PCApplySymmetricLeft_Cholesky in src/ksp/pc/impls/factor/cholesky/cholesky.c</A><BR>
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/ksp/pc/impls/factor/icc/icc.c.html#PCApplySymmetricLeft_ICC">PCApplySymmetricLeft_ICC in src/ksp/pc/impls/factor/icc/icc.c</A><BR>
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/ksp/pc/impls/factor/ilu/ilu.c.html#PCApplySymmetricLeft_ILU">PCApplySymmetricLeft_ILU in src/ksp/pc/impls/factor/ilu/ilu.c</A><BR>
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/ksp/pc/impls/shell/shellpc.c.html#PCApplySymmetricLeft_Shell">PCApplySymmetricLeft_Shell in src/ksp/pc/impls/shell/shellpc.c</A><BR>


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[Edit on GitLab](https://gitlab.com/petsc/petsc/-/edit/release/src/ksp/pc/interface/precon.c)


[Index of all PC routines](index.md)  
[Table of Contents for all manual pages](/manualpages/index.md)  
[Index of all manual pages](/manualpages/singleindex.md)