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# MatGetInfo
Returns information about matrix storage (number of nonzeros, memory, etc.). 
## Synopsis
```
#include "petscmat.h" 
PetscErrorCode MatGetInfo(Mat mat, MatInfoType flag, MatInfo *info)
```
Collective if `MAT_GLOBAL_MAX` or `MAT_GLOBAL_SUM` is used as the flag


## Input Parameters

- ***mat -*** the matrix
- ***flag -*** flag indicating the type of parameters to be returned (`MAT_LOCAL` - local matrix, `MAT_GLOBAL_MAX` - maximum over all processors, `MAT_GLOBAL_SUM` - sum over all processors)



## Output Parameter

- ***info -*** matrix information context



## Options Database Key

- ***-mat_view ::ascii_info -*** print matrix info to `PETSC_STDOUT`



## Notes
The `MatInfo` context contains a variety of matrix data, including
number of nonzeros allocated and used, number of mallocs during
matrix assembly, etc.  Additional information for factored matrices
is provided (such as the fill ratio, number of mallocs during
factorization, etc.).


## Example
See the file ${PETSC_DIR}/include/petscmat.h for a complete list of
data within the MatInfo context.  For example,
```none
      MatInfo info;
      Mat     A;
      double  mal, nz_a, nz_u;

      MatGetInfo(A, MAT_LOCAL, &info);
      mal  = info.mallocs;
      nz_a = info.nz_allocated;
```


Fortran users should declare info as a double precision
array of dimension `MAT_INFO_SIZE`, and then extract the parameters
of interest.  See the file ${PETSC_DIR}/include/petsc/finclude/petscmat.h
a complete list of parameter names.
```none
      double  precision info(MAT_INFO_SIZE)
      double  precision mal, nz_a
      Mat     A
      integer ierr

      call MatGetInfo(A, MAT_LOCAL, info, ierr)
      mal = info(MAT_INFO_MALLOCS)
      nz_a = info(MAT_INFO_NZ_ALLOCATED)
```





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


## See Also
 [](ch_matrices), `Mat`, `MatInfo`, `MatStashGetInfo()`

## Level
intermediate

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

## Examples
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/mat/tutorials/ex16.c.html">src/mat/tutorials/ex16.c</A><BR>

## Implementations

<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/mat/impls/aij/mpi/mpiaij.c.html#MatGetInfo_MPIAIJ">MatGetInfo_MPIAIJ in src/mat/impls/aij/mpi/mpiaij.c</A><BR>
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/mat/impls/aij/mpi/mumps/mumps.c.html#MatGetInfo_MUMPS">MatGetInfo_MUMPS in src/mat/impls/aij/mpi/mumps/mumps.c</A><BR>
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/mat/impls/aij/mpi/pastix/pastix.c.html#MatGetInfo_PaStiX">MatGetInfo_PaStiX in src/mat/impls/aij/mpi/pastix/pastix.c</A><BR>
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/mat/impls/aij/seq/aij.c.html#MatGetInfo_SeqAIJ">MatGetInfo_SeqAIJ in src/mat/impls/aij/seq/aij.c</A><BR>
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/mat/impls/baij/mpi/mpibaij.c.html#MatGetInfo_MPIBAIJ">MatGetInfo_MPIBAIJ in src/mat/impls/baij/mpi/mpibaij.c</A><BR>
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/mat/impls/baij/seq/baij2.c.html#MatGetInfo_SeqBAIJ">MatGetInfo_SeqBAIJ in src/mat/impls/baij/seq/baij2.c</A><BR>
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/mat/impls/cdiagonal/cdiagonal.c.html#MatGetInfo_ConstantDiagonal">MatGetInfo_ConstantDiagonal in src/mat/impls/cdiagonal/cdiagonal.c</A><BR>
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/mat/impls/dense/mpi/mpidense.c.html#MatGetInfo_MPIDense">MatGetInfo_MPIDense in src/mat/impls/dense/mpi/mpidense.c</A><BR>
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/mat/impls/dense/seq/dense.c.html#MatGetInfo_SeqDense">MatGetInfo_SeqDense in src/mat/impls/dense/seq/dense.c</A><BR>
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/mat/impls/elemental/matelem.cxx.html#MatGetInfo_Elemental">MatGetInfo_Elemental in src/mat/impls/elemental/matelem.cxx</A><BR>
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/mat/impls/is/matis.c.html#MatGetInfo_IS">MatGetInfo_IS in src/mat/impls/is/matis.c</A><BR>
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/mat/impls/sbaij/mpi/mpisbaij.c.html#MatGetInfo_MPISBAIJ">MatGetInfo_MPISBAIJ in src/mat/impls/sbaij/mpi/mpisbaij.c</A><BR>
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/mat/impls/sbaij/seq/cholmod/sbaijcholmod.c.html#MatGetInfo_CHOLMOD">MatGetInfo_CHOLMOD in src/mat/impls/sbaij/seq/cholmod/sbaijcholmod.c</A><BR>
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/mat/impls/sbaij/seq/sbaij2.c.html#MatGetInfo_SeqSBAIJ">MatGetInfo_SeqSBAIJ in src/mat/impls/sbaij/seq/sbaij2.c</A><BR>
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/mat/impls/scalapack/matscalapack.c.html#MatGetInfo_ScaLAPACK">MatGetInfo_ScaLAPACK in src/mat/impls/scalapack/matscalapack.c</A><BR>
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/mat/impls/sell/mpi/mpisell.c.html#MatGetInfo_MPISELL">MatGetInfo_MPISELL in src/mat/impls/sell/mpi/mpisell.c</A><BR>
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/mat/impls/sell/seq/sell.c.html#MatGetInfo_SeqSELL">MatGetInfo_SeqSELL in src/mat/impls/sell/seq/sell.c</A><BR>


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