Re: [boost] RE: Standardization of Boost libraries

From: Beman Dawes (bdawes_at_[hidden])
Date: 2002-03-10 17:31:03

At 05:27 AM 3/8/2002, Moore, Paul wrote:

 >> I'd say the discussion tended toward a 'yes' answer, but
 >> some people weren't sure; they thought rational numbers
 >> might be close to the boundary between 'yes' and 'no', and
 >> wanted to see a few more clearcut cases before making a
 >> decision.
 >
 >Makes sense. My point of view is that of an (ex-) mathematician, looking 
at
 >the library from a completeness point of view. In that context, having
 >complex numbers, but not rationals, seems odd. And from a 
non-mathematical
 >practical computing position, I have never needed complex numbers, but 
have
 >occasionally wanted rationals. (Although, in practice, I have always been
 >able to work around not having rationals, so I can't say I've ever had a
 >serious problem with the lack...)
 >
 >My experience from the actual implementation process is that, without an
 >unlimited-precision integer type on which to base the rational class, the
 >usefulness of rational<> is drastically diminished. Both double and
 >rational<int> have subtle rounding, precision, and other issues. With
 >double, these properties are fairly well-known, especially by the sort of
 >people who are likely to hit them. With rational<int>, they are *not* 
well
 >known. On the contrary, the sort of people who might use rational<int> 
are
 >very likely to completely miss the fact that there are such problems. (I
 >nearly did, until I started doing the actual implementation!)
 >
 >It's arguable that these sort of issues make rational<> inappropriate for
 >the standard library. And it's *definitely* arguable that
 >unlimited-precision integers are more appropriate, and should be 
considered
 >first. (One slight issue - there's no candidate implementation of
 >unlimited-precision integers, yet!)

That sounds reasonable.  If you would like, I'll ask the committee to table 
rational pending unlimited-precision integers.

--Beman