Re: [pure-lang-users] complex 0

[Albert G. <Dr....@t-...>]

Eddie Rucker wrote:
> What about ln 1? Scheme has a different philosophy from Pure: all
> operations *try* to return an exact value if the operation's argument(s)
> are exact.

That's true, of course. But in the case ln 0 there's no exact result. In 
fact, Scheme's approach to this raises many difficult questions, because 
it's not clear immediately what, in a precise mathematical sense, should 
be an exact result. That borders on computer algebra which is a *very* 
difficult area which goes way beyond just rational numbers and the like.

> I think I've totally
> chased the rabbit away from my original question which was about
> consistency for which you found the answer in a later post.

I agree, that should be the goal. And in fact you've been right, the 
definitions in math.pure have some bugs there.

There are many tradeoffs in numerical mathematics, even more so in 
computer algebra, design decisions are difficult, and sometimes I'm not 
even aware of them. So please continue to raise those questions, that 
always gives me an opportunity to rethink those things!

Thanks,
Albert

-- 
Dr. Albert Gr"af
Dept. of Music-Informatics, University of Mainz, Germany
Email:  Dr....@t-..., ag...@mu...
WWW:    http://www.musikinformatik.uni-mainz.de/ag