public static double deltaVectors(
	double[] vec1,
	double[] vec2 )
{
	double[] test = Vector.sub(vec1, vec2);
	double delta = 0.0;
	int m = vec1.length;
	for ( int i = 0; i < m; ++i )
		delta += Math.abs(test[i]);
	return(delta / m);
}