[std-interval] C++ interval std

[Lawrence.Crowl at Sun.com]

Sylvain Pion <Sylvain.Pion at sophia.inria.fr> writes:
 >Well, if we're arguing that passsing-by-value is fundamentally important
 >for speed, and that adding a few more tests is not because speed is less
 >important... ;)

Pass-by-value is also a correctness issue.

 >> Uninitialized.  The convention in C/C++ is to initialize to zero,
 >> but we agree that is not correct for intervals.  Whole is probably
 >> the best we can do.
 >
 >I'm not convinced.  Initilization to [0,0] seems nice to me for
 >intervals because of homogeneity reasons with floating-point.
 >I could even imagine that the empty interval would make as much
 >sense as whole.
 >
 >What makes you think that [0,0] is "not correct", and why 'whole'
 >would be better than 'empty' ?

Note that on modern systems, initialization to [0,0] is more efficient.

 >>    Quad precision
 >>        (Should C++ IA standard quad intervals?)
 >
 >I would say that it depends if quads appear in the C++ language
 >(or is this supposed to be the already existing "long double" ?).
 >But if they appear, probably support for interval<quads> should
 >be added, yes.

The meaning of long double is implementation-dependent.  On Solaris
SPARC, it is 128 bits.  On Solaris x86, it is 80 bits.

 >More generally, since IEEE754R will most probably be released before
 >C++0x, it would be nice if C++0x would take it into account.

An explicit mention of IEEE754R in the C++ standard will require a
paper.

  Lawrence Crowl             650-786-6146   Sun Microsystems, Inc.
                   Lawrence.Crowl at Sun.com   16 Network Circle, UMPK16-303
           http://www.Crowl.org/Lawrence/   Menlo Park, California, 94025