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# MatCreateSeqBAIJMKL
Creates a sparse matrix of type `MATSEQBAIJMKL`. This type inherits from `MATSEQBAIJ` and is largely identical, but uses sparse BLAS routines from Intel MKL whenever possible. 
## Synopsis
```
PetscErrorCode MatCreateSeqBAIJMKL(MPI_Comm comm, PetscInt bs, PetscInt m, PetscInt n, PetscInt nz, const PetscInt nnz[], Mat *A)
```

## Input Parameters

- ***comm -*** MPI communicator, set to `PETSC_COMM_SELF`
- ***bs -*** size of block, the blocks are ALWAYS square. One can use `MatSetBlockSizes()` to set a different row and column blocksize but the row
blocksize always defines the size of the blocks. The column blocksize sets the blocksize of the vectors obtained with `MatCreateVecs()`
- ***m -*** number of rows
- ***n -*** number of columns
- ***nz -*** number of nonzero blocks  per block row (same for all rows)
- ***nnz -*** array containing the number of nonzero blocks in the various block rows
(possibly different for each block 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, `MatSeqBAIJSetPreallocation()`]


## Options Database Keys

- ***-mat_no_unroll -*** uses code that does not unroll the loops in the block calculations (much slower)
- ***-mat_block_size -*** size of the blocks to use





## Notes
The number of rows and columns must be divisible by blocksize.

If the `nnz` parameter is given then the `nz` parameter is ignored

A nonzero block is any block that as 1 or more nonzeros in it

`MatMult()`, `MatMultAdd()`, `MatMultTranspose()`, and `MatMultTransposeAdd()`
operations are currently supported.
If the installed version of MKL supports the "SpMV2" sparse
inspector-executor routines, then those are used by default.
Default PETSc kernels are used otherwise.

The `MATSEQBAIJ` format 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 the users' manual for details.

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 [Sparse Matrices](sec_matsparse) for details.
matrices.


## See Also
 [Sparse Matrices](sec_matsparse), `MatCreate()`, `MatCreateSeqAIJ()`, `MatSetValues()`, `MatCreateBAIJ()`

## Level
intermediate

## Location
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/mat/impls/baij/seq/baijmkl/baijmkl.c.html#MatCreateSeqBAIJMKL">src/mat/impls/baij/seq/baijmkl/baijmkl.c</A>


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[Edit on GitLab](https://gitlab.com/petsc/petsc/-/edit/release/src/mat/impls/baij/seq/baijmkl/baijmkl.c)


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