# mkl_dcoomm

Computes matrix-matrix product of a sparse matrix stored in the coordinate format.

## Syntax

Fortran:

call mkl_dcoomm(transa, m, n, k, alpha, matdescra, val, rowind, colind, nnz, b, ldb, beta, c, ldc)

C:

mkl_dcoomm(&transa, &m, &n, &k, &alpha, matdescra, val, rowind, colind, &nnz, b, &ldb, &beta, c, &ldc);

## Description

The mkl_dcoomm routine performs a matrix-matrix operation defined as
`C := alpha*A*B + beta*C`

or
`C := alpha*A'*B + beta*C,`

where:

alpha and beta are scalars,

B and C are dense matrices, A is an m-by-k sparse matrix in the coordinate format, A' is the transpose of A.

### Note

This routine supports coordinate format both with one-based indexing and zero-based indexing.

## Input Parameters

Parameter descriptions are common for all implemented interfaces with the exception of data types that refer here to the FORTRAN 77 standard types. Data types specific to the different interfaces are described in the section “Interfaces” below.

transa

  CHARACTER*1. Specifies the operation.

  If `transa = 'N'` or 'n', then `C := alpha*A*B + beta*C`

  If `transa = 'T'` or 't' or 'C' or 'c', then `C := alpha*A'*B + beta*C`,

m

  INTEGER. Number of rows of the matrix A.

n

  INTEGER. Number of columns of the matrix C.

k

  INTEGER. Number of columns of the matrix A.

alpha

  REAL*8. Specifies the scalar alpha.

matdescra

  CHARACTER. Array of six elements, specifies properties of the matrix used for operation. Only first four array elements are used, their possible values are given in the “Possible Values of the Parameter matdescra (descra)”.

val

  REAL*8. Array of length nnz, contains non-zero elements of the matrix A in the arbitrary order.

  Refer to values array description in Coordinate Format for more details.

rowind

  INTEGER. Array of length nnz, contains the row indices for each non-zero element of the matrix A.

  Refer to rows array description in Coordinate Format for more details.

colind

  INTEGER. Array of length nnz, contains the column indices for each non-zero element of the matrix A. Refer to columns array description in Coordinate Format for more details.

nnz

  INTEGER. Specifies the number of non-zero element of the matrix A.

  Refer to nnz description in Coordinate Format for more details.

b

  REAL*8.

  Array, DIMENSION `(ldb, n)` for one-based indexing, and `(m, ldb)` for zero-based indexing.

  On entry with `transa = 'N'` or 'n', the leading k-by-n part of the array b must contain the matrix B, otherwise the leading m-by-n part of the array b must contain the matrix B.

ldb

  INTEGER. Specifies the first dimension of b for one-based indexing, and the second dimension of b for zero-based indexing, as declared in the calling (sub)program.

beta

  REAL*8. Specifies the scalar beta.

c

  REAL*8.

  Array, DIMENSION (ldc, n) for one-based indexing, and `(m, ldc)` for zero-based indexing.

  On entry, the leading m-by-n part of the array c must contain the matrix C, otherwise the leading k-by-n part of the array c must contain the matrix C.

ldc

  INTEGER. Specifies the first dimension of c for one-based indexing, and the second dimension of c for zero-based indexing, as declared in the calling (sub)program.

## Output Parameters

c

  Overwritten by the matrix `(alpha*A*B + beta*C)` or `(alpha*A'*B + beta*C)`.

## Interfaces

## FORTRAN 77:

SUBROUTINE mkl_dcoomm(transa, m, n, k, alpha, matdescra, val,

rowind, colind, nnz, b, ldb, beta, c, ldc)

CHARACTER*1 transa

CHARACTER matdescra(*)

INTEGER m, n, k, ldb, ldc, nnz

INTEGER rowind(*), colind(*)

REAL*8 alpha, beta

REAL*8 val(*), b(ldb,*), c(ldc,*)

## C:

`void mkl_dcoomm(char *transa, int *m, int *n, int *k, double *alpha,`
`char *matdescra, double *val, int *rowind, int *colind, int *nnz,`
`double *b, int *ldb, double *beta, double *c, int *ldc);`

Parent topic: Sparse BLAS Level 2 and Level 3 Routines.