:orphan:
# PCMGMatResidualTransposeDefault
Default routine to calculate the residual of the transposed linear system 
## Synopsis
```
#include "petscksp.h" 
PetscErrorCode PCMGMatResidualTransposeDefault(Mat mat, Mat b, Mat x, Mat r)
```
Collective


## Input Parameters

- ***mat -*** the matrix
- ***b   -*** the right-hand-side
- ***x   -*** the approximate solution



## Output Parameter

- ***r -*** location to store the residual





## See Also
 `PCMG`, `PCMGSetMatResidualTranspose()`

## Level
developer

## Location
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/ksp/pc/impls/mg/mgfunc.c.html#PCMGMatResidualTransposeDefault">src/ksp/pc/impls/mg/mgfunc.c</A>


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


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