:orphan:
# TaoComputeResidual
Computes a least-squares residual vector at a given point 
## Synopsis
```
#include "petsctao.h" 
PetscErrorCode TaoComputeResidual(Tao tao, Vec X, Vec F)
```
Collective


## Input Parameters

- ***tao -*** the `Tao` context
- ***X -*** input vector



## Output Parameter

- ***f -*** Objective vector at `X`





## Notes
`TaoComputeResidual()` is typically used within the implementation of the optimization algorithm,
so most users would not generally call this routine themselves.


## See Also
 [](ch_tao), `Tao`, `TaoSetResidualRoutine()`

## Level
advanced

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


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