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# MatCreateSeqAIJViennaCL
Creates a sparse matrix in `MATSEQAIJVIENNACL` (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 MatCreateSeqAIJViennaCL(MPI_Comm comm, PetscInt m, PetscInt n, PetscInt nz, const PetscInt nnz[], Mat *A)
```
Collective


## Input Parameters

- ***comm -*** MPI communicator, set to `PETSC_COMM_SELF`
- ***m -*** number of rows
- ***n -*** number of columns
- ***nz -*** number of nonzeros per row (same for all rows), ignored if `nnz` is set
- ***nnz -*** array containing the number of nonzeros in the various rows (possibly different for each row) or `NULL`



## Output Parameter

- ***A -*** the matrix


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


## Notes
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.

Specify the preallocated storage with either `nz` or `nnz` (not both).
Set `nz` = `PETSC_DEFAULT` and `nnz` = `NULL` for PETSc to control dynamic memory
allocation.




## See Also
 `MATSEQAIJVIENNACL`, `MatCreate()`, `MatCreateAIJ()`, `MatCreateAIJCUSPARSE()`, `MatSetValues()`, `MatSeqAIJSetColumnIndices()`, `MatCreateSeqAIJWithArrays()`, `MatCreateAIJ()`

## Level
intermediate

## Location
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/mat/impls/aij/seq/seqviennacl/aijviennacl.cxx.html#MatCreateSeqAIJViennaCL">src/mat/impls/aij/seq/seqviennacl/aijviennacl.cxx</A>


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[Edit on GitLab](https://gitlab.com/petsc/petsc/-/edit/release/src/mat/impls/aij/seq/seqviennacl/aijviennacl.cxx)


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