Is there a way to get a hashcode of a float with epsilon?

Question

It is well known that comparing floats by == is usually a mistake. In a 3D-vector class (with float components X, Y, Z) i wrote, two vectors are considered equa

Answer 1

I don't think you can have a hashcode that is consistent with your comparison method because the latter is not transitive: for any three vectors A, B, C, if A.Equals(B) and B.Equals(C) are true, it could still be the case that A.Equals(C) is false. (Imagine if the distance between A and B is 6e-6, between B and C is 6e-6, and between A and C is 1.2e-5) But equality of hashcodes is always transitive, since they're just numbers.

In this case, I'd just create a hashcode method that computes the hash based on the exact values of the floating-point coordinates, and mention in the documentation that it's inconsistent with equals. I know it's not really a solution but given that I don't think a real solution exists, it's better to have a nontrivial hashcode than just 0.