Re: [Maxima-discuss] Use Lisp complex numbers in Maxima?

[Richard F. <fa...@be...>]

On 4/1/2016 6:45 PM, Stavros Macrakis (Σταῦρος Μακράκης) wrote:
> If you want to talk mathematics, why not think in terms of isomorphism 
> rather than identity?
>
> Maxima complexes are /isomorphic/ to Lisp complexes.

Not quite..
the Re and Im parts of a Maxima complex can be  bigfloats or symbols or 
expressions. e.g. cos(x)+%i*sin(x).
A CL complex must have components that are CL numbers.

This morning I'm thinking that a CL complex display could be something 
that indicates
it is somehow CL.
Earlier,   I put together a display for intervals so they print like 
<1..3>,  so a user
would not be so tempted to use inpart()  and such.

If CL complexes are another example,  maybe
we need something more general, that hints of exotic representation.
e.g.
  <# interval, 1,3>
<# complex, 1, 3>
<# otherstructure,1,2,3,4>

thus we could create a CL complex with  ?complex(1,3)  and the resulting 
atom would
be displayed as <# complex , 1, 3>.

(I suppose, with matchfix, we could even allow typing that, but the 
result would
still be an atom...)



> They have the same algebraic properties. That doesn't mean that Maxima 
> complexes must be represented as Lisp complexes.
>
This is true.
RJF

>            -s
>
> On Fri, Apr 1, 2016 at 9:24 PM, Robert Dodier <rob...@gm... 
> <mailto:rob...@gm...>> wrote:
>
>     On 2016-04-01, Stavros Macrakis <mac...@al...
>     <mailto:mac...@al...>> wrote:
>
>     > I don't think mathematics says anything about how to use the features of a
>     > programming language to build a new abstraction. If Maxima were
>     written in
>     > C, would you give users access to untyped pointers? (Hmm, scary
>     to think
>     > that you might...)
>
>     Ha, don't tempt me. Clearly the answer is yes, if untyped pointers
>     have
>     any algebraic properties of interest ... 8^)
>
>     best
>
>     Robert Dodier
>
>
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