# TaoADMMSetRegularizerHessianRoutine
Sets the user-defined regularizer Hessian call-back function, to be used for subsolverZ. 
## Synopsis
```
#include "petsctao.h" 
PetscErrorCode TaoADMMSetRegularizerHessianRoutine(Tao tao, Mat H, Mat Hpre, PetscErrorCode (*func)(Tao, Vec, Mat, Mat, void *), void *ctx)
```
Collective


## Input Parameters

- ***tao -*** the Tao context
- ***H -*** user-created matrix for the Hessian of the regularization term
- ***Hpre -*** user-created matrix for the preconditioner of Hessian of the regularization term
- ***func -*** function pointer for the regularizer Hessian evaluation
- ***ctx -*** user context for the regularizer Hessian





## See Also
 `TAOADMM`


## Level
advanced

## Location
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/tao/constrained/impls/admm/admm.c.html#TaoADMMSetRegularizerHessianRoutine">src/tao/constrained/impls/admm/admm.c</A>

## Examples
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/tao/constrained/tutorials/tomographyADMM.c.html">src/tao/constrained/tutorials/tomographyADMM.c.html</A><BR>


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


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