At 9:57 PM -0700 1/4/07, Doug McNutt wrote:

At 18:23 -0800 1/4/07, Dave Whipp wrote:Darren Duncan wrote:For example, the extra space of putting them aside will let usexpand them to make them more thorough, such as dealing well withexact vs inexact, fixed vs infinite length, fuzzy or intervalbased vs not, caring about sigfigs or not, real vs complex vsquaternon, etc.>I agree with the general idea that this is non core (from animplementatin perspective); but one thing struck me here (slightlyoff topic, but not too far): a quaternion cannot be a Num becauseanyone using a "Num" will assume that multiplication is commutative(for quaternions, $a*$b != $b*$a).Quaternions are much more like vectors - real ones - where we havebeen before.Vectors, matrices, tensors, and symmetry groups should not be corebut the procedures for overloading operators so that they can beimplemented as add-ins should be ready to use and easy for asimple-minded mathematician to implement.

`FYI, my mentioning of quaternions was a throwaway example, based on`

`the assumption from context that they were to complex what complex`

`was to real; please ignore that detail in my post. -- Darren Duncan`