function daxpy( N, alpha, x, strideX, y, strideY ) {
	var ix;
	var iy;
	if ( N <= 0 || alpha === 0.0 ) {
		return y;
	}
	ix = stride2offset( N, strideX );
	iy = stride2offset( N, strideY );
	return ndarray( N, alpha, x, strideX, ix, y, strideY, iy );
}
Multiplies a vector `x` by a constant and adds the result to `y`.

@param {PositiveInteger} N - number of indexed elements
@param {number} alpha - scalar
@param {Float64Array} x - input array
@param {integer} strideX - `x` stride length
@param {Float64Array} y - output array
@param {integer} strideY - `y` stride length
@returns {Float64Array} output array

@example
var Float64Array = require( '@stdlib/array/float64' );

var x = new Float64Array( [ 1.0, 2.0, 3.0, 4.0, 5.0 ] );
var y = new Float64Array( [ 1.0, 1.0, 1.0, 1.0, 1.0 ] );
var alpha = 5.0;

daxpy( x.length, alpha, x, 1, y, 1 );
// y => <Float64Array>[ 6.0, 11.0, 16.0, 21.0, 26.0 ]