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# TSComputeRHSJacobianConstant
Reuses a Jacobian that is time-independent.
## Synopsis
```
#include "petscts.h"
PetscErrorCode TSComputeRHSJacobianConstant(TS ts, PetscReal t, Vec U, Mat A, Mat B, void *ctx)
```
Collective
## Input Parameters
- ***ts -*** time stepping context
- ***t -*** time at which to evaluate
- ***U -*** state at which to evaluate
- ***ctx -*** context
## Output Parameters
- ***A -*** pointer to operator
- ***B -*** pointer to preconditioning matrix
## Note
This function is intended to be passed to `TSSetRHSJacobian()` to evaluate the Jacobian for linear time-independent problems.
## See Also
[](ch_ts), `TS`, `TSSetRHSFunction()`, `TSSetRHSJacobian()`, `TSComputeRHSFunctionLinear()`
## Level
intermediate
## Location
src/ts/interface/ts.c
## Examples
src/tao/unconstrained/tutorials/spectraladjointassimilation.c
src/ts/tutorials/ex3.c
src/ts/tutorials/ex4.c
src/ts/tutorials/ex5.c
src/ts/tutorials/ex6.c
src/ts/tutorials/ex74.c
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