# MatCreateLaplacian
Create the matrix Laplacian, with all values in the matrix less than the tolerance set to zero 
## Synopsis
```
#include <petscmat.h> 
PetscErrorCode MatCreateLaplacian(Mat A, PetscReal tol, PetscBool weighted, Mat *L)
```

## Input Parameters

- ***A   -*** The matrix
- ***tol -*** The zero tolerance
- ***weighted -*** Flag for using edge weights



## Output Parameters

- ***L -*** The graph Laplacian matrix





## See Also
 `MatChop()`, `MatGetGraph()`

## Level
intermediate

## Location
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/mat/order/spectral.c.html#MatCreateLaplacian">src/mat/order/spectral.c</A>


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[Edit on GitLab](https://gitlab.com/petsc/petsc/-/edit/release/src/mat/order/spectral.c)


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