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Date: Thu, 16 Mar 2000 14:50:16 +0100 (MET)
From: Hans-Bernhard Broeker <broeker AT physik DOT rwth-aachen DOT de>
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To: djgpp-workers AT delorie DOT com
cc: Martin Stromberg <Martin DOT Stromberg AT lu DOT erisoft DOT se>
Subject: Re: Unnormals???
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On Thu, 16 Mar 2000, Eli Zaretskii wrote:

> 
> On Wed, 15 Mar 2000, Martin Stromberg wrote:
> 
> > > Perhaps you tried without the sign in the format specifier?  That case 
> > > was left alone on purpose; see the discussions on djgpp-workers about 10 
> > > months ago (IIRC).
> > 
> > But the sign of a negative nan and inf should be printed regardless of
> > any sign format specifier.
> 
> Why ``should''?  I don't think the standard says that, since some
> architectures don't support signed NaNs.

That doesn't really matter. To cite the draft C99, on the '+'
option to printf format specs:

       +     The result of a signed conversion always begins with a
             plus or minus sign.  (It begins with a sign only  when
             a  negative  value  is  converted  if this flag is not
             specified.)258)

and the footnote:

       258The results of all floating  conversions  of  a  negative
          zero,  and of negative values that round to zero, include
          a minus sign.

So, if a particular NaN is 'a negative value', it should have a minus in
front of it. The syntax of describing a printf() output by "[-]something"
is used throughout the printf() definition, so I think there's no option
for interpreting "[-]nan" any different from the other cases, here.

And just to bring that into the discussion, again: *printf() is not the
only place we'ld have to have to do something about, here.
"[-]nan(optional_string)" is supposed to be usable by other functions,
too, including *scanf(), strtod and the new nan*() functions.


Hans-Bernhard Broeker (broeker AT physik DOT rwth-aachen DOT de)
Even if all the snow were burnt, ashes would remain.