# mkl_cspblas_dcoogemv

Computes matrix - vector product of a sparse general matrix stored in the coordinate format with zero-based indexing.

## Syntax

Fortran:

call mkl_cspblas_dcoogemv(transa, m, val, rowind, colind, nnz, x, y)

C:

mkl_cspblas_dcoogemv(&transa, &m, val, rowind, colind, &nnz, x, y);

## Description

The mkl_cspblas_dcoogemv routine performs a matrix-vector operation defined as
`y := A*x`

or
`y := A'*x,`

where:

x and y are vectors,

A is an m-by-m sparse square matrix in the coordinate format with zero-based indexing, A' is the transpose of A.

### Note

This routine supports only zero-based indexing of the input arrays.

## 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 the matrix-vector product is computed as `y := A*x`

  If `transa = 'T'` or 't' or 'C' or 'c', then the matrix-vector product is computed as `y := A'*x`,

m

  INTEGER. Number of rows of the matrix A.

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.

x

  REAL*8.

  Array, DIMENSION is m.

  On entry, the array x must contain the vector x.

## Output Parameters

y

  REAL*8.

  Array, DIMENSION at least m.

  On exit, the array y must contain the vector y.

## Interfaces

## FORTRAN 77:

SUBROUTINE mkl_cspblas_dcoogemv(transa, m, val, rowind, colind, nnz, x, y)

CHARACTER*1 transa

INTEGER m, nnz

INTEGER rowind(*), colind(*)

REAL*8 val(*), x(*), y(*)

## C:

`void mkl_cspblas_dcoogemv(char *transa, int *m, double *val, int *rowind,`
`int *colind, int *nnz, double *x, double *y);`

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