title: Good Hash function with 2 integer for a special key
body: <p>I'm trying to determine a key for <code>map&lt;double, double&gt;</code> type. But the problem is that the key I want will be generated by a pair of 2 numbers. Are there any good functions which could generate such key for pairs like (0, 1), (2, 3), (4, 2) (0, 2), etc. </p>