# naginterfaces.library.sparse.direct_​real_​gen_​matmul¶

naginterfaces.library.sparse.direct_real_gen_matmul(trans, alpha, icolzp, irowix, a, b, beta, c=None)[source]

direct_real_gen_matmul computes a matrix-matrix or transposed matrix-matrix product involving a real, square, sparse nonsymmetric matrix stored in compressed column (Harwell–Boeing) format.

For full information please refer to the NAG Library document for f11mk

https://www.nag.com/numeric/nl/nagdoc_28.5/flhtml/f11/f11mkf.html

Parameters
transstr, length 1

Specifies whether or not the matrix is transposed.

is computed.

is computed.

alphafloat

, the scalar factor in the matrix multiplication.

icolzpint, array-like, shape

The new column index array of sparse matrix . See the F11 Introduction.

irowixint, array-like, shape

The row index array of sparse matrix . See the F11 Introduction.

afloat, array-like, shape

The array of nonzero values in the sparse matrix .

bfloat, array-like, shape

The matrix .

betafloat

The scalar factor .

cNone or float, array-like, shape , optional

The matrix .

Returns
cfloat, ndarray, shape

is overwritten by or depending on the value of .

Raises
NagValueError
(errno )

On entry, .

Constraint: .

(errno )

On entry, .

Constraint: .

(errno )

On entry, .

Constraint: or .

Notes

direct_real_gen_matmul computes either the matrix-matrix product , or the transposed matrix-matrix product , according to the value of the argument , where is a real sparse nonsymmetric matrix, of arbitrary sparsity pattern with nonzero elements, and are real dense matrices. The matrix is stored in compressed column (Harwell–Boeing) storage format. The array stores all nonzero elements of , while arrays and store the compressed column indices and row indices of respectively.