default double distance(final Vec<T> other, final int index) {
		return distance().distance(data(), other.data(), index);
	}
Calculates the distance between two vector elements at the given
{@code index}.

@param other the second vector
@param index the vector element index
@return the distance between two vector elements
@throws NullPointerException if the {@code other} vector is {@code null}
@throws IllegalArgumentException if the {@code index} is out of the valid
        range {@code [0, length())}
jenetics.ext/src/main/java/io/jenetics/ext/moea/Vec.java