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# MatCreateAIJViennaCL
Creates a sparse matrix in `MATAIJ` (compressed row) format (the default parallel PETSc format).  This matrix will ultimately be pushed down to GPUs and use the ViennaCL library for calculations. 
## Synopsis
```
#include "petscmat.h" 
PetscErrorCode MatCreateAIJViennaCL(MPI_Comm comm, PetscInt m, PetscInt n, PetscInt M, PetscInt N, PetscInt d_nz, const PetscInt d_nnz[], PetscInt o_nz, const PetscInt o_nnz[], Mat *A)
```
Collective


## Input Parameters

- ***comm -*** MPI communicator, set to `PETSC_COMM_SELF`
- ***m -*** number of rows, or `PETSC_DECIDE` if `M` is provided
- ***n -*** number of columns, or `PETSC_DECIDE` if `N` is provided
- ***M -*** number of global rows in the matrix, or `PETSC_DETERMINE` if `m` is provided
- ***N -*** number of global columns in the matrix, or `PETSC_DETERMINE` if `n` is provided
- ***d_nz  -*** number of nonzeros per row in DIAGONAL portion of local submatrix
(same value is used for all local rows)
- ***d_nnz -*** array containing the number of nonzeros in the various rows of the
DIAGONAL portion of the local submatrix (possibly different for each row)
or `NULL`, if `d_nz` is used to specify the nonzero structure.
The size of this array is equal to the number of local rows, i.e `m`.
For matrices you plan to factor you must leave room for the diagonal entry and
put in the entry even if it is zero.
- ***o_nz  -*** number of nonzeros per row in the OFF-DIAGONAL portion of local
submatrix (same value is used for all local rows).
- ***o_nnz -*** array containing the number of nonzeros in the various rows of the
OFF-DIAGONAL portion of the local submatrix (possibly different for
each row) or `NULL`, if `o_nz` is used to specify the nonzero
structure. The size of this array is equal to the number
of local rows, i.e `m`.



## Output Parameter

- ***A -*** the matrix





## Notes
It is recommended that one use the `MatCreate()`, `MatSetType()` and/or `MatSetFromOptions()`,
MatXXXXSetPreallocation() paradigm instead of this routine directly.
[MatXXXXSetPreallocation() is, for example, `MatSeqAIJSetPreallocation()`]

The AIJ format, also called
compressed row storage), is fully compatible with standard Fortran
storage.  That is, the stored row and column indices can begin at
either one (as in Fortran) or zero.


## See Also
 `Mat`, `MatCreate()`, `MatCreateAIJ()`, `MatCreateAIJCUSPARSE()`, `MatSetValues()`, `MatSeqAIJSetColumnIndices()`, `MatCreateSeqAIJWithArrays()`,
`MatCreateAIJ()`, `MATMPIAIJVIENNACL`, `MATAIJVIENNACL`

## Level
intermediate

## Location
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/mat/impls/aij/mpi/mpiviennacl/mpiaijviennacl.cxx.html#MatCreateAIJViennaCL">src/mat/impls/aij/mpi/mpiviennacl/mpiaijviennacl.cxx</A>


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[Edit on GitLab](https://gitlab.com/petsc/petsc/-/edit/release/src/mat/impls/aij/mpi/mpiviennacl/mpiaijviennacl.cxx)


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