Affine transforms - matrix algebra: equals

[Richard Bair]

> I think that a more conventional approach would be to implement both equals(Object) and hashCode(). There is plenty of mutable JDK classes implementing those methods (including HashMap itself! and all other standard collection implementations), so I would tend to believe that a majority of experienced Java developers know that they must not change any object stored as keys in such map...

If only Java were also concerned with those inexperienced Java developers, we might have seen a different pattern emerge ;-)