function sum( arr ) {
	var len;
	var out;
	var i;

	len = arr.length;
	out = 0.0;
	for ( i = 0; i < len; i++ ) {
		out += arr[ i ];
	}
	return out;
}
Computes the sum of elements of an numeric array.

@private
@param {NumericArray} arr - input array
@returns {number} sum

@example
var arr = [ 2.0, 6.0, 10.0 ];
var out = sum( arr );
// returns 18.0