On Nov 23, 10:28 am, Rock <[EMAIL PROTECTED]> wrote:
> I think the best bet would be implementing them in Clojure itself. I'm
> saying this because otherwise it would really get harder given the
> constraints regarding immutability. Furthermore, the implementation
> should, I think, be generic, that is, we should be capable of creating
> complex numbers, the real and imaginary parts of which can be
> integers, rationals, or reals. For instance, it sould be possible to
> do this:
>
> (1/3 + 2/5i) + (1/2 + 1/10i) = (5/6 + 1/2i)
>
> without any loss of precision due to type conversion (ex. towards
> float).
>
> So, from what I gather, a good choice might be to use structures, and
> perhaps multimethods.
>
> Rich, would it be possible to "overload" the arithmetic operators with
> this strategy, so that they'll work with the new complex numbers?
>
> Opinions?
There's likely to be performance pressure on any numeric types.
Rich
>
> On Nov 23, 3:42 pm, Rich Hickey <[EMAIL PROTECTED]> wrote:
>
> > On Nov 23, 8:56 am, Rock <[EMAIL PROTECTED]> wrote:
>
> > > On Nov 23, 2:37 pm, André Thieme <[EMAIL PROTECTED]> wrote:
>
> > > > On 23 Nov., 13:29, Rock <[EMAIL PROTECTED]> wrote:
>
> > > > > I've just noticed there is no support for complex numbers in Clojure.
> > > > > There are a few posts on the issue here, but no rationale. I'm a
> > > > > mathematician, and complex numbers pop up all over the place. CL and
> > > > > Scheme have always had native support for them. I took it for granted
> > > > > they were there until I needed them recently.
>
> > > > I think the reason is, that Java still does not have them in its
> > > > standard lib. It puzzles my why they didn’t come up with
> > > > something in the past 13 years.
> > > > If you want them you will have to use some lib for that.
>
> > > Yes, I see, but the JVM hasn't got native support for rational numbers
> > > either, and yet we do have them in Clojure thanks to the Ratio class
> > > Rich created. I can't see why something analogous can't be done for
> > > complex numbers as well. We even have unbound integers! And you don't
> > > have them in Java natively. Maybe, for the time being, some Complex
> > > class like the ones found in Apache.Commons or in JScience could be
> > > incorporated into Clojure, so that we have a common basis to work on,
> > > and there would be compatibility among different people's code
> > > (somthing important I believe).
>
> > I have nothing against complex numbers, and interested parties should
> > contribute to this discussion on how best to incorporate them in
> > Clojure. The issues are:
>
> > What support is required?
> > How hard to do with no other libs, a la Ratio?
> > If a 3rd-party lib is required, which one, what's the license, how to
> > make it optional, how well does it fit with Clojure's immutability
> > requirements, etc.
>
> > I'm amenable to a patch after consensus, but it's not something I have
> > time to do myself.
>
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