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# MatQRFactorNumeric
Performs numeric QR factorization of a matrix. Call this routine after first calling `MatGetFactor()`, and `MatQRFactorSymbolic()`. 
## Synopsis
```
#include "petscmat.h" 
PetscErrorCode MatQRFactorNumeric(Mat fact, Mat mat, const MatFactorInfo *info)
```
Collective


## Input Parameters

- ***fact -*** the factor matrix obtained with `MatGetFactor()`
- ***mat -*** the matrix
- ***info -*** options for factorization





## Notes
See `MatQRFactor()` for in-place factorization.

Most users should employ the `KSP` interface for linear solvers
instead of working directly with matrix algebra routines such as this.
See, e.g., `KSPCreate()`.


## Developer Note
The Fortran interface is not autogenerated as the
interface definition cannot be generated correctly [due to `MatFactorInfo`]


## See Also
 [](ch_matrices), `Mat`, [Matrix Factorization](sec_matfactor), `MatFactorInfo`, `MatGetFactor()`, `MatQRFactor()`, `MatQRFactorSymbolic()`, `MatLUFactor()`

## Level
developer

## Location
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/mat/interface/matrix.c.html#MatQRFactorNumeric">src/mat/interface/matrix.c</A>

## Implementations

<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/mat/impls/aij/seq/spqr/aijspqr.c.html#MatQRFactorNumeric_SPQR">MatQRFactorNumeric_SPQR in src/mat/impls/aij/seq/spqr/aijspqr.c</A><BR>
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/mat/impls/dense/seq/dense.c.html#MatQRFactorNumeric_SeqDense">MatQRFactorNumeric_SeqDense in src/mat/impls/dense/seq/dense.c</A><BR>


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