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RE: [Axiom-mail] complex numbers
From: |
Bill Page |
Subject: |
RE: [Axiom-mail] complex numbers |
Date: |
Wed, 29 Dec 2004 01:36:54 -0500 |
On Wednesday, December 29, 2004 1:17 AM Bob McElrath wrote:
>
> Andrea Bedini address@hidden wrote:
> > Hi,
> > I'm just learning how to do some computations with Axiom,
> > but I've a problem with complex numbers.
> >
> > Why this evalutate to zero ?
> >
> > (199) -> A: Complex Polynomial Integer
> >
> Type: Void
> > (200) -> A*conjugate A - A^2
> >
> > (200) 0
>
> Definitely wrong. It looks like the source of the problem is:
>
> (18) -> conjugate(a)
>
> (18) a
> Type: Complex Polynomial Integer
>
Of course I agree that it is wrong. But what would you expect
the answer to be?
conjugate(a)
could return unevaluated as just
conjugate(a)
but then what should the Type: be? Is such an expression
still necessarily a Complex Polynomial Integer?
This is dangerously close to the discussion that we had some
months ago about the meaning of "indeterminants", objects
which have a type but no specific value. For example, I can
say
A:Integer
but if I write
A+1
If you answered "yes" to the idea that conjugate(a) is still
of type Complex Polynomial Integer, then surely A+1 is still
of type Integer is the same sense, but Axiom complains that
"A has not been given a value".
Perhaps evaluating the expression
conjugate(a)
should also complain about the lack of a value?
Regards,
Bill Page.