@Override
	public int hashCode() {
		int hash = 17;
		hash += 31*Double.hashCode(_x) + 37;
		hash += 31*Double.hashCode(_y) + 37;
		return hash;
	}
Return the <em>y</em> value of the point.

@return the <em>y</em> value of the point
jenetics.ext/src/test/java/io/jenetics/ext/moea/Point2.java