# HPL_daxpy - Man Page

y := y + alpha * x.

## Synopsis

`#include "hpl.h" void HPL_daxpy( const int N, const double ALPHA, const double * X, const int INCX, double * Y, const int INCY );`

## Description

HPL_daxpy scales the vector x by alpha and adds it to y.

## Arguments

N       (local input)           const int

On entry, N specifies the length of the vectors  x  and  y. 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 the entries of the incremented array X need not be set on input.

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.

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. On exit, the entries of the incremented array  Y  are updated with the scaled entries of the incremented array X.

INCY    (local input)           const int

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

## Example

#include "hpl.h"
int main(int argc, char *argv[])
{
double x, y;
x = 1.0; x = 2.0; x = 3.0;
y = 4.0; y = 5.0; y = 6.0;
HPL_daxpy( 3, 2.0, x, 1, y, 1 );
printf("y=[%f,%f,%f]\n", y, y, y);
exit(0); return(0);
}

## See Also

HPL_dcopy (3), HPL_dscal (3), HPL_dswap (3).

## Referenced By

February 24, 2016 HPL 2.2 HPL Library Functions