# Name

**HPL_daxpy**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[3], y[3]; x[0] = 1.0; x[1] = 2.0; x[2] = 3.0; y[0] = 4.0; y[1] = 5.0; y[2] = 6.0; HPL_daxpy( 3, 2.0, x, 1, y, 1 ); printf("y=[%f,%f,%f]\n", y[0], y[1], y[2]); exit(0); return(0); }