function dfill( N, alpha, x, strideX, offsetX ) {
	var ix;
	var m;
	var i;

	if ( N <= 0 ) {
		return x;
	}
	ix = offsetX;

	// Use loop unrolling if the stride is equal to `1`...
	if ( strideX === 1 ) {
		m = N % M;

		// If we have a remainder, run a clean-up loop...
		if ( m > 0 ) {
			for ( i = 0; i < m; i++ ) {
				x[ ix ] = alpha;
				ix += strideX;
			}
		}
		if ( N < M ) {
			return x;
		}
		for ( i = m; i < N; i += M ) {
			x[ ix ] = alpha;
			x[ ix+1 ] = alpha;
			x[ ix+2 ] = alpha;
			x[ ix+3 ] = alpha;
			x[ ix+4 ] = alpha;
			x[ ix+5 ] = alpha;
			x[ ix+6 ] = alpha;
			x[ ix+7 ] = alpha;
			ix += M;
		}
		return x;
	}
	for ( i = 0; i < N; i++ ) {
		x[ ix ] = alpha;
		ix += strideX;
	}
	return x;
}
Fills a double-precision floating-point strided array with a specified scalar constant.

@param {PositiveInteger} N - number of indexed elements
@param {number} alpha - scalar constant
@param {Float64Array} x - input array
@param {integer} strideX - stride length
@param {NonNegativeInteger} offsetX - starting index
@returns {Float64Array} input array

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

var x = new Float64Array( [ 1.0, -2.0, 3.0, -4.0, 5.0, -6.0 ] );

dfill( 3, 5.0, x, 1, x.length-3 );
// x => <Float64Array>[ 1.0, -2.0, 3.0, 5.0, 5.0, 5.0 ]