:orphan:
# TaoResidualMonitor
Views the least-squares residual at each iteration of `TaoSolve()` 
## Synopsis
```
#include "petsctao.h" 
PetscErrorCode TaoResidualMonitor(Tao tao, void *ctx)
```
Collective


## Input Parameters

- ***tao -*** the `Tao` context
- ***ctx -*** the `PetscViewer` context or `NULL`



## Options Database Key

- ***-tao_view_ls_residual -*** view the residual at each iteration





## See Also
 [](ch_tao), `Tao`, `TaoDefaultSMonitor()`, `TaoSetMonitor()`

## Level
advanced

## Location
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/tao/interface/taosolver.c.html#TaoResidualMonitor">src/tao/interface/taosolver.c</A>


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


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