# MatDFischer
Calculates an element of the B-subdifferential of the Fischer-Burmeister function for complementarity problems. 
## Synopsis
```
#include "petsctao.h" 
PetscErrorCode MatDFischer(Mat jac, Vec X, Vec Con, Vec XL, Vec XU, Vec T1, Vec T2, Vec Da, Vec Db)
```
Collective


## Input Parameters

- ***jac -*** the jacobian of f at X
- ***X -*** current point
- ***Con -*** constraints function evaluated at X
- ***XL -*** lower bounds
- ***XU -*** upper bounds
- ***t1 -*** work vector
- ***t2 -*** work vector



## Output Parameters

- ***Da -*** diagonal perturbation component of the result
- ***Db -*** row scaling component of the result





## See Also
 `Mat`, `VecFischer()`, `VecSFischer()`, `MatDSFischer()`

## Level
developer

## Location
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/tao/util/tao_util.c.html#MatDFischer">src/tao/util/tao_util.c</A>


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


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