# SNESSetConvergenceHistory
Sets the array used to hold the convergence history. 
## Synopsis
```
#include "petscsnes.h"  
PetscErrorCode SNESSetConvergenceHistory(SNES snes, PetscReal a[], PetscInt its[], PetscInt na, PetscBool reset)
```
Logically Collective on snes


## Input Parameters

- ***snes -*** iterative context obtained from `SNESCreate()`
- ***a   -*** array to hold history, this array will contain the function norms computed at each step
- ***its -*** integer array holds the number of linear iterations for each solve.
- ***na  -*** size of a and its
- ***reset -*** `PETSC_TRUE` indicates each new nonlinear solve resets the history counter to zero,
else it continues storing new values for new nonlinear solves after the old ones



## Notes
If 'a' and 'its' are NULL then space is allocated for the history. If 'na' `PETSC_DECIDE` or `PETSC_DEFAULT` then a
default array of length 10000 is allocated.

This routine is useful, e.g., when running a code for purposes
of accurate performance monitoring, when no I/O should be done
during the section of code that is being timed.




## See Also
 `SNES`, `SNESSolve()`, `SNESGetConvergenceHistory()`

## Level
intermediate

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


---
[Edit on GitLab](https://gitlab.com/petsc/petsc/-/edit/release/src/snes/interface/snes.c)


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