- From: Per Bothner <per@bothner.com>
- Date: Wed, 10 Dec 2003 09:04:39 -0800
- To: Jim Melton <jim.melton@acm.org>
- Cc: Damien Fisher <damien@sodatech.com>, www-ql@w3.org, public-qt-comments@w3.org
Jim Melton wrote: > retain the numerator > and denominator themselves, thus effectively holding "1/3" exactly. I > know of a couple of (very old, research) languages that do this, but > they are rather complicated and cumbersome. Common Lisp et al does that, though it simplifies fractions: 6/4 -> 3/2. There is certainly more prior art for this than for repeating decimals, but I think repeating decimals would be more usefully integrated into "enterprise" applications. Common Lisp may be old and unfashionable, but it is an industrial-strength production language. And while parts of it may be complicated, its numerics aren't particularly complicated. Many Scheme implementations (including mine) also support exact rationals, and Scheme is really a small language. If your language supports infinite-precision integers then supporting exact rationals seems a reasonable extension. Damien@sodatech.com wrote: > My example wasn't the best. What I am trying to say is that repeatedly > performing a division a / b (with b > a) can very quickly lead to > unbounded growth in the height of the answer, whereas this is not the > case with floating point or integer division. > > Controlling this can be difficult. It does not mean exact rationals > have no uses, just that they are not as useful as many people expect. Agreed. That is why *also* want to support floating point numbers, as Common Lisp and Scheme do. (Scheme doesn't specify floating point numbers, but calls them "inexact real" numbers.) And as XQuery/Schema also does. -- --Per Bothner per@bothner.com http://per.bothner.com/
Received on Wednesday, 10 December 2003 12:08:55 UTC