[Top][All Lists]
[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: [Help-gsl] IEEE doubles/ANSI C questions
From: |
Brian Gough |
Subject: |
Re: [Help-gsl] IEEE doubles/ANSI C questions |
Date: |
Fri, 29 Oct 2004 16:30:10 +0100 |
Michael Mair writes:
> Even if we for a moment assume that C doubles on the considered
> architectures are IEEE doubles, there is the still the
> overprecision on x86 systems, so the result will of course not
> be the same if -ffloat-store is not used (which OTOH would
> deteriorate the performance considerably).
Hello,
x86 chips can be put in double precision mode (which is much more
efficient than -ffloat-store). It happens that the default with most
operating systems is to use extended precision mode, but it's not
necessary. See the IEEE chapter for details.
> Is there a better rationale why one should not prefer long
> double?
The size of double is specifically defined (52bit mantissa), while
long double size is always implementation dependent.
> Now, I would like to know whether there are experiences or
> known problems using GSL with C99 (or the gcc C99 subset
> available by gcc -std=c99 -pedantic). The semantics of the
> inline keyword differ in gcc -std=gnu89 and C99, but maybe the
> referred-to extended autoconf checking helps finding out
> whether this works or not.
I haven't tested it with -std=c99 -pedantic but I wouldn't expect any
problems.
--
best regards
Brian Gough
(GSL Maintainer)
Network Theory Ltd,
Commercial support for GSL --- http://www.network-theory.co.uk/gsl/