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 us
expand them to make them more thorough, such as dealing well with
exact vs inexact, fixed vs infinite length, fuzzy or interval
based vs not, caring about sigfigs or not, real vs complex vs
quaternon, etc.
>I agree with the general idea that this is non core (from an
implementatin perspective); but one thing struck me here (slightly
off topic, but not too far): a quaternion cannot be a Num because
anyone 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 have
been before.
Vectors, matrices, tensors, and symmetry groups should not be core
but the procedures for overloading operators so that they can be
implemented as add-ins should be ready to use and easy for a
simple-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
