# DMSNESCheckJacobian
Check the Jacobian of the exact solution against the residual using the Taylor Test 
## Synopsis
```
#include "petscdmplex.h" 
#include "petscsnes.h"   
PetscErrorCode DMSNESCheckJacobian(SNES snes, DM dm, Vec u, PetscReal tol, PetscBool *isLinear, PetscReal *convRate)
```

## Input Parameters

- ***snes -*** the `SNES` object
- ***dm   -*** the `DM`
- ***u    -*** a `DM` vector
- ***tol  -*** A tolerance for the check, or -1 to print the results instead



## Output Parameters

- ***isLinear -*** Flag indicaing that the function looks linear, or NULL
- ***convRate -*** The rate of convergence of the linear model, or NULL





## See Also
 `DNSNESCheckFromOptions()`, `DMSNESCheckDiscretization()`, `DMSNESCheckResidual()`

## Level
developer

## Location
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/snes/utils/dmplexsnes.c.html#DMSNESCheckJacobian">src/snes/utils/dmplexsnes.c</A>


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


[Index of all SNES routines](index.md)  
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[Index of all manual pages](/docs/manualpages/singleindex.md)  
