# SNESMonitorRatio
Monitors progress of the `SNES` solvers by printing the ratio of residual norm at each iteration to the previous. 
## Synopsis
```
#include "petsc/private/snesimpl.h"   
PetscErrorCode SNESMonitorRatio(SNES snes, PetscInt its, PetscReal fgnorm, PetscViewerAndFormat *vf)
```
Collective on snes


## Input Parameters

- ***snes -*** the `SNES` context
- ***its -*** iteration number
- ***fgnorm -*** 2-norm of residual (or gradient)
- ***dummy -*** context of monitor



## Option Database Key

- ***-snes_monitor_ratio -*** activate this monitor





## Notes
This is not called directly by users, rather one calls `SNESMonitorSet()`, with this function as an argument, to cause the monitor
to be used during the `SNES` solve.

Be sure to call `SNESMonitorRationSetUp()` before using this monitor.


## See Also
 `SNESMonitorRationSetUp()`, `SNESMonitorSet()`, `SNESMonitorSolution()`, `SNESMonitorDefault()`

## Level
intermediate

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


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