:orphan:
# DMPlexLandauIFunction
TS residual calculation, confusingly this computes the Jacobian w/o mass 
## Synopsis
```
#include "petscdmplex.h" 
#include "petsclandau.h"   
PetscErrorCode DMPlexLandauIFunction(TS ts, PetscReal time_dummy, Vec X, Vec X_t, Vec F, void *actx)
```
Collective


## Input Parameters

- ***TS  -*** The time stepping context
- ***time_dummy -*** current time (not used)
- ***X -*** Current state
- ***X_t -*** Time derivative of current state
- ***actx -*** Landau context



## Output Parameter

- ***F  -*** The residual




.keywords: mesh

## See Also
 `DMPlexLandauCreateVelocitySpace()`, `DMPlexLandauIJacobian()`

## Level
beginner

## Location
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/ts/utils/dmplexlandau/plexland.c.html#DMPlexLandauIFunction">src/ts/utils/dmplexlandau/plexland.c</A>

## Examples
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/ts/utils/dmplexlandau/tutorials/ex1.c.html">src/ts/utils/dmplexlandau/tutorials/ex1.c</A><BR>
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/ts/utils/dmplexlandau/tutorials/ex1f90.F90.html">src/ts/utils/dmplexlandau/tutorials/ex1f90.F90</A><BR>
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/ts/utils/dmplexlandau/tutorials/ex2.c.html">src/ts/utils/dmplexlandau/tutorials/ex2.c</A><BR>


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


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