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

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

This reminds me of a set of bugs I reported in Wolfram's Mathematica. A 
while ago.

Maybe the simplest indication is that (still, in Mathematica 10)
Head[3+4 I]   returns Complex
Head[a+b I]    returns Plus

this means that a pattern   a_+b_ I
does NOT match 3+4 I    but does match x+y*I.

If you want to match 3+4 I  you can use a pattern     Z_Complex

but either of these two  fails if you want to  3+x+ 4 I  to match.
So you need a third.

Bringing us back to Maxima ... the Common Lisp objects for
complex numbers and for rationals  are viewed as "atoms" and so
all the Maxima code that looks for lists beginning with  mplus and involving
$%i  to identify complex numbers,  and for lists beginning with rat for
rationals ... have to be augmented somehow.
RJF



   On 4/1/2016 5:58 AM, Barton Willis wrote:
>
> >PS The case for Lisp rationals is a little different, but not hugely 
> so. The performance gains are smaller,
>
>
> CL complex numbers would automatically give us rectangular form for 
> complex number arithmetic. That would be nice. Likely the least 
> disruptive way to achieve this wouldn't be to allow naked CL complex 
> numbers to be Maxima expressions, but to squeeze code into simplus and 
> friends.
>
>
> --Barton
>
>
>
>
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