# 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, 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);
}
```