# MatLMVMClearJ0
Removes all definitions of J0 and reverts to an identity matrix (scale = 1.0). 
## Synopsis
```
#include "petscksp.h" 
PetscErrorCode MatLMVMClearJ0(Mat B)
```

## Input Parameters

- ***B -*** An LMVM-type matrix





## See Also
 [](chapter_ksp), [LMVM Matrices](sec_matlmvm), `MATLMVM`, `MatLMVMSetJ0()`

## Level
advanced

## Location
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/ksp/ksp/utils/lmvm/lmvmutils.c.html#MatLMVMClearJ0">src/ksp/ksp/utils/lmvm/lmvmutils.c</A>


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[Edit on GitLab](https://gitlab.com/petsc/petsc/-/edit/release/src/ksp/ksp/utils/lmvm/lmvmutils.c)


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