NAME

HPL_dger - A := alpha * x * y^T + A.

SYNOPSIS

#include "hpl.h"

void HPL_dger( const enum HPL_ORDER ORDER, const int M, const int N, const double ALPHA, const double * X, const int INCX, double * Y, const int INCY, double * A, const int LDA );

DESCRIPTION

HPL_dger performs the rank 1 operation

A := alpha * x * y^T + A,

where alpha is a scalar, x is an m-element vector, y is an n-element vector and A is an m by n matrix.

ARGUMENTS

ORDER (local input) const enum HPL_ORDER

On entry, ORDER specifies the storage format of the operands as follows:
ORDER = HplRowMajor,
ORDER = HplColumnMajor.

M (local input) const int

On entry, M specifies the number of rows of the matrix A. M must be at least zero.

N (local input) const int

On entry, N specifies the number of columns of the matrix A. N must be at least zero.

ALPHA (local input) const double

On entry, ALPHA specifies the scalar alpha. When ALPHA is supplied as zero then X and Y need not be set on input.

X (local input) const double *

On entry, X is an incremented array of dimension at least ( 1 + ( m - 1 ) * abs( INCX ) ) that contains the vector x.

INCX (local input) const int

On entry, INCX specifies the increment for the elements of X. INCX must not be zero.

Y (local input) double *

On entry, Y is an incremented array of dimension at least ( 1 + ( n - 1 ) * abs( INCY ) ) that contains the vector y.

INCY (local input) const int

On entry, INCY specifies the increment for the elements of Y. INCY must not be zero.

A (local input/output) double *

On entry, A points to an array of size equal to or greater than LDA * n. Before entry, the leading m by n part of the array A must contain the matrix coefficients. On exit, A is overwritten by the updated matrix.

LDA (local input) const int

On entry, LDA specifies the leading dimension of A as declared in the calling (sub) program. LDA must be at least MAX(1,m).

EXAMPLE

#include "hpl.h"

int main(int argc, char *argv[])
{
double a[2*2], x[2], y[2];
a[0] = 1.0; a[1] = 2.0; a[2] = 3.0; a[3] = 3.0;
x[0] = 2.0; x[1] = 1.0; y[2] = 1.0; y[3] = 2.0;
HPL_dger( HplColumnMajor, 2, 2, 2.0, x, 1, y, 1,
a, 2 );
printf("y=[%f,%f]\n", y[0], y[1]);
exit(0); return(0);
}

SEE ALSO

HPL_dgemv (3), HPL_dtrsv (3).