Date: Thu, 23 Apr 1998 14:30:38 +0200 From: Hans-Bernhard Broeker Message-Id: <199804231230.OAA11215@acp3bf.physik.rwth-aachen.de> To: pderbysh AT usa DOT net (Paul Derbyshire) Cc: djgpp AT delorie DOT com Subject: Re: Spotting NaNs Newsgroups: comp.os.msdos.djgpp Organization: RWTH Aachen, III. physikalisches Institut B Precedence: bulk In article <353F141B DOT 24547B62 AT usa DOT net> you wrote: > I also noticed neither isnan() nor isnanf() appear to be ANSI or > POSIX. I don't think they can possibly be. After all, there's nothing that would guarantee that there even _is_ such a thing as a NaN on every possible platform. (But rumor has it that the requirement of such IEEE 754 compatibility may be added to the next of the ANSI C Standard, nicknamed C9X). > Are they widely supported? Or a Gnu extension? Widely supported: yes, I'ld say (just checked on Linux, Solaris, DEC Unix, DEC Ultrix, and SGI's IRIX). According to one of those systems' man pages, it's defined by 'XPG4' (by X/Open, a Unix standardisation effort). Certainly no GNU extension. Generally, I'ld guess you'll find isnan() & friends on every system with an IEEE 754 compatible floating point system. -- Hans-Bernhard Broeker (broeker AT physik DOT rwth-aachen DOT de) Even if all the snow were burnt, ashes would remain.