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# TaoSetConvergenceHistory
Sets the array used to hold the convergence history. 
## Synopsis
```
#include "petsctao.h" 
PetscErrorCode TaoSetConvergenceHistory(Tao tao, PetscReal obj[], PetscReal resid[], PetscReal cnorm[], PetscInt lits[], PetscInt na, PetscBool reset)
```
Logically Collective


## Input Parameters

- ***tao -*** the `Tao` solver context
- ***obj   -*** array to hold objective value history
- ***resid -*** array to hold residual history
- ***cnorm -*** array to hold constraint violation history
- ***lits -*** integer array holds the number of linear iterations for each Tao iteration
- ***na  -*** size of `obj`, `resid`, and `cnorm`
- ***reset -*** `PETSC_TRUE` indicates each new minimization resets the history counter to zero,
else it continues storing new values for new minimizations after the old ones





## Notes
If set, `Tao` will fill the given arrays with the indicated
information at each iteration.  If 'obj','resid','cnorm','lits' are
*all* `NULL` then space (using size `na`, or 1000 if na is `PETSC_DECIDE` or
`PETSC_DEFAULT`) is allocated for the history.
If not all are `NULL`, then only the non-`NULL` information categories
will be stored, the others will be ignored.

Any convergence information after iteration number 'na' will not be stored.

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
 [](ch_tao), `TaoGetConvergenceHistory()`

## Level
intermediate

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

## Examples
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/tao/leastsquares/tutorials/chwirut1.c.html">src/tao/leastsquares/tutorials/chwirut1.c</A><BR>
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/tao/leastsquares/tutorials/chwirut1f.F90.html">src/tao/leastsquares/tutorials/chwirut1f.F90</A><BR>
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/tao/leastsquares/tutorials/cs1.c.html">src/tao/leastsquares/tutorials/cs1.c</A><BR>
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/tao/leastsquares/tutorials/tomography.c.html">src/tao/leastsquares/tutorials/tomography.c</A><BR>


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


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