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[Help-gsl] IEEE doubles/ANSI C questions

From: Michael Mair
Subject: [Help-gsl] IEEE doubles/ANSI C questions
Date: Tue, 26 Oct 2004 12:00:39 +0200
User-agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.4) Gecko/20030624 Netscape/7.1

Hi there,

I have just read through the introduction of the GSL manual and
have now two questions:
- the use of double variables is advocated over the use of long
  double variables with the reasoning that doubles were IEEE
  doubles and thus the same on all machines.
  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).
  Is there a better rationale why one should not prefer long
- The introduction talks about "ANSI C" but evidently means C89
  (as it claims that there were no inline functions in ANSI C
  which is wrong as of C99 which is the current ANSI C standard).
  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.
It would be very kind if someone would answer these questions or
refer me to the right place to ask them.

Thanks in advance

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