# SNESKSPSetParametersEW
Sets parameters for Eisenstat-Walker convergence criteria for the linear solvers within an inexact Newton method. 
## Synopsis
```
#include "petscsnes.h"  
PetscErrorCode SNESKSPSetParametersEW(SNES snes, PetscInt version, PetscReal rtol_0, PetscReal rtol_max, PetscReal gamma, PetscReal alpha, PetscReal alpha2, PetscReal threshold)
```
Logically Collective on snes


## Input Parameters

- ***snes -*** `SNES` context
- ***version -*** version 1, 2 (default is 2), 3 or 4
- ***rtol_0 -*** initial relative tolerance (0 <= rtol_0 < 1)
- ***rtol_max -*** maximum relative tolerance (0 <= rtol_max < 1)
- ***gamma -*** multiplicative factor for version 2 rtol computation
(0 <= gamma2 <= 1)
- ***alpha -*** power for version 2 rtol computation (1 < alpha <= 2)
- ***alpha2 -*** power for safeguard
- ***threshold -*** threshold for imposing safeguard (0 < threshold < 1)



## Notes
Version 3 was contributed by Luis Chacon, June 2006.

Use `PETSC_DEFAULT` to retain the default for any of the parameters.




## See Also
 `SNES`, `SNESKSPSetUseEW()`, `SNESKSPGetUseEW()`, `SNESKSPGetParametersEW()`

## Level
advanced

## Location
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/snes/interface/snes.c.html#SNESKSPSetParametersEW">src/snes/interface/snes.c</A>


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