Bill Page wrote:
>
> On Wed, Oct 22, 2008 at 2:07 AM, Martin Rubey wrote:
> > ...
> > div2exquo : F -> F
> > div2exquo f ==
> > -- one?(d := denom f) => f
> > ((d := denom f) = 1) => f
> > opex(smp2exquo numer f, smp2exquo d)
> >
> > (by the way, I think we should replace (* = 1) by one?(*) again)
> >
>
> Perhaps it needs more discussion, but I agree that removing the code
> 'one? ...' and 'zero? ...' throughout the library source was probably
> a mistake. I recall some discussions with Tim about this in the very
> early days of the open source project.
>
> http://lists.nongnu.org/archive/html/axiom-developer/2003-07/msg00103.html
>
> My point of view was that it introduces a deep and unnecessary
> dependency. Tim suggested that this was an "optimization" introduced
> by NAG:
>
> http://lists.nongnu.org/archive/html/axiom-developer/2003-07/msg00107.html
>
ATM I have no strong opinion about 'one? ...' and 'zero? ...'.
However, they have really nothing to do with CCL -- they are Spad
functions which for some domains may be given some special Lisp
implementation. Both are just special case of eqality. 'one? ...'
and 'zero? ...' in principle may be slightly more efficient than
general equality because frequently 0 and 1 have very special
representation. Also, 0 and 1 sometimes are special cases for
equality, so we may get deeper recursion (and there is some
risk of infinite loops). OTOH using just equality mathematically
looks cleaner.
--
Waldek Hebisch
[EMAIL PROTECTED]
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