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# TSRKSetMultirate
Use the interpolation-based multirate `TSRK` method 
## Synopsis
```
#include "petscts.h"   
PetscErrorCode TSRKSetMultirate(TS ts, PetscBool use_multirate)
```
Logically Collective


## Input Parameters

- ***ts -*** timestepping context
- ***use_multirate -*** `PETSC_TRUE` enables the multirate `TSRK` method, sets the basic method to be RK2A and sets the ratio between slow stepsize and fast stepsize to be 2



## Options Database Key

- ***-ts_rk_multirate -*** <true,false>





## Note
The multirate method requires interpolation. The default interpolation works for 1st- and 2nd- order RK, but not for high-order RKs except `TSRK5DP` which comes with the interpolation coefficients (binterp).


## See Also
 [](ch_ts), `TSRK`, `TSRKGetMultirate()`

## Level
intermediate

## Location
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/ts/impls/explicit/rk/rk.c.html#TSRKSetMultirate">src/ts/impls/explicit/rk/rk.c</A>

## Implementations

<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/ts/impls/explicit/rk/mrk.c.html#TSRKSetMultirate_RK">TSRKSetMultirate_RK in src/ts/impls/explicit/rk/mrk.c</A><BR>


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[Edit on GitLab](https://gitlab.com/petsc/petsc/-/edit/release/src/ts/impls/explicit/rk/rk.c)


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