# mkl_dcoosm

Solves a system of linear matrix equations for a sparse matrix in the coordinate format.

## Syntax

Fortran:

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

C:

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

## Description

The mkl_dcoosm routine solves a system of linear equations with matrix-matrix operations for a sparse matrix in the coordinate format:
`C := alpha*inv(A)*B`

or
`C := alpha*inv(A')*B,`

where:

alpha is scalar, B and C are dense matrices, A is a sparse upper or lower triangular matrix with unit or non-unit main diagonal, 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 system of linear equations.

  If `transa = 'N'` or 'n', then the matrix-matrix product is computed as `C := alpha*inv(A)*B`

  If `transa = 'T'` or 't' or 'C' or 'c', then the matrix-vector product is computed as `C := alpha*inv(A')*B`,

m

  INTEGER. Number of rows of the matrix A.

n

  INTEGER. Number of columns of the matrix C.

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”.

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.

  Before entry 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.

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

  REAL*8.

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

  The leading m-by-n part of the array c contains the output matrix C.

## Interfaces

## FORTRAN 77:

SUBROUTINE mkl_dcoosm(transa, m, n, alpha, matdescra, val, rowind, colind, nnz, b, ldb, c, ldc)

CHARACTER*1 transa

CHARACTER matdescra(*)

INTEGER m, n, ldb, ldc, nnz

INTEGER rowind(*), colind(*)

REAL*8 alpha

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

## C:

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

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