Hi I had a look last night at making Quaternion a VALJO.
I've done the following * changed the constructors to private and added equivalent of methods. * added a parse method * altered equals so that (like Complex) it uses Double.equals - gets round an edge case where Quaternions with the equivalence of -0 and 0 discovered while adding tests for hashCode * added a divide by scalar method * added a norm2 (square of norm) method * added some additional unit tests so it should now have 100% coverage I've raised a pull request, and I have also emailed an ICLA. I think two convenience divide methods performing qr^{-1} and r^{-1}q for q and r would be useful, but I couldn't think of nice names for them. Steve