# TSAlpha2SetParams
sets the algorithmic parameters for `TSALPHA2` 
## Synopsis
```
#include "petscts.h"   
PetscErrorCode TSAlpha2SetParams(TS ts, PetscReal alpha_m, PetscReal alpha_f, PetscReal gamma, PetscReal beta)
```
Logically Collective on ts


## Second-order accuracy can be obtained so long as
\gamma = 1/2 + alpha_m - alpha_f
\beta  = 1/4 (1 + alpha_m - alpha_f)^2


## Unconditional stability requires
\alpha_m >= \alpha_f >= 1/2


## Input Parameters

- ***ts -*** timestepping context
- ***\alpha_m -*** algorithmic parameter
- ***\alpha_f -*** algorithmic parameter
- ***\gamma   -*** algorithmic parameter
- ***\beta    -*** algorithmic parameter



## Options Database Keys

- ***-ts_alpha_alpha_m <alpha_m> -*** set alpha_m
- ***-ts_alpha_alpha_f <alpha_f> -*** set alpha_f
- ***-ts_alpha_gamma   <gamma> -*** set gamma
- ***-ts_alpha_beta    <beta> -*** set beta





## Note
Use of this function is normally only required to hack `TSALPHA2` to
use a modified integration scheme. Users should call
`TSAlpha2SetRadius()` to set the desired spectral radius of the methods
(i.e. high-frequency damping) in order so select optimal values for
these parameters.


## See Also
 [](chapter_ts), `TS`, `TSALPHA2`, `TSAlpha2SetRadius()`, `TSAlpha2GetParams()`

## Level
advanced

## Location
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/ts/impls/implicit/alpha/alpha2.c.html#TSAlpha2SetParams">src/ts/impls/implicit/alpha/alpha2.c</A>

## Implementations

<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/ts/impls/implicit/alpha/alpha2.c.html#TSAlpha2SetParams_Alpha">TSAlpha2SetParams_Alpha in src/ts/impls/implicit/alpha/alpha2.c</A><BR>


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[Edit on GitLab](https://gitlab.com/petsc/petsc/-/edit/release/src/ts/impls/implicit/alpha/alpha2.c)


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