HPL_dgemv - y := beta * y + alpha * op(A) * x.
#include "hpl.h"
void HPL_dgemv( const enum HPL_ORDER ORDER,
const
enum HPL_TRANS TRANS,
const int M,
const int
N,
const double ALPHA,
const double * A,
const int LDA,
const double * X,
const int
INCX,
const double BETA,
double * Y,
const int INCY );
HPL_dgemv performs one of the matrix-vector operations
y := alpha * op( A ) * x + beta * y,
where op( X ) is one of
op( X ) = X or op( X ) = X^T.
where alpha and beta are scalars, x and y are vectors and A is an m by n matrix.
- ORDER (local input) const enum HPL_ORDER
- On entry, ORDER specifies the storage format of the operands as follows:
ORDER = HplRowMajor,
ORDER = HplColumnMajor.
- TRANS (local input) const enum HPL_TRANS
- On entry, TRANS specifies the operation to be performed as follows:
TRANS = HplNoTrans y := alpha*A *x + beta*y,
TRANS = HplTrans y := alpha*A^T*x + beta*y.
- 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 A and X need not be set on input.
- A (local input) const 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.
- 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).
- X (local input) const double *
- On entry, X is an incremented array of dimension at least ( 1 + ( n - 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.
- BETA (local input) const double
- On entry, BETA specifies the scalar beta. When ALPHA is supplied as zero
then Y need not be set on input.
- Y (local input/output) double *
- On entry, Y is an incremented array of dimension at least ( 1 + ( n - 1 )
* abs( INCY ) ) that contains the vector y. Before entry with BETA
non-zero, the incremented array Y must contain the vector y. On exit, Y is
overwritten by the updated vector y.
- INCY (local input) const int
- On entry, INCY specifies the increment for the elements of Y. INCY must
not be zero.
#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_dgemv( HplColumnMajor, HplNoTrans, 2, 2, 2.0,
a, 2, x, 1, -1.0, y, 1 );
printf("y=[%f,%f]\n", y[0], y[1]);
exit(0); return(0);
}
HPL_dger (3),
HPL_dtrsv (3).