evaluating erf(%i) in maxima



This does get back to the issue of how to interface with Common Lisp numbers.

We could have a category, in Maxima, of
"Common Lisp Numbers"  which would include #c(1.2 0.5),
which is considered to be an atom by lisp.

a+b*%i is not a numeric constant, nor is  1.2+0.5%i, meaning...
((mplus) 1.2 ((mtimes) 0.5 $%i)). This is a lisp list.

This also happens with rational numbers, available in CL.

We could have a program that attempts to common-lispify all
possible numbers, and then do arithmetic using the common-lisp
programs like sin, cos, .. when possible.
Caution, though. In Allegro common lisp,
(sin 1/2) returns a float 0.47942555
(sin 0.5d0) returns 0.479425538604203d0.

RJF



Raymond Toy wrote:

>>>>>>"Stavros" == Stavros Macrakis  writes:
> 
> 
>     Stavros> Hmm.  I guess I was too terse.  If you want to be completely consistent
>     Stavros> with base Maxima, it should not give a numerical value, since
>     Stavros> sin(0.5*%i+1.2),numer doesn't, either.  But that can be argued to be
>     Stavros> wrong.  So it seems fine to me that gamma(1+1/2*%i),numer should give a
>     Stavros> complex float, and maybe sin should be changed, too....
> 
> Oh, right.  I see what you're getting at.  And yes, it does annoy me
> that sin(1.2+0.5*%i) doesn't give a number, and it would be nice if
> that were changed.
> 
> Ray
> 
> 
> 
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