[vox-tech] location of DBL_EPSILON definition
Peter Jay Salzman
p at dirac.org
Fri Jan 26 11:36:34 PST 2007
On Fri 26 Jan 07, 8:39 AM, Micah Cowan <micah at cowan.name> said:
> On Fri, 2007-01-26 at 08:24 -0500, Peter Jay Salzman wrote:
> > Where is DBL_EPSILON defined? I thought it was in float.h. But I've looked
> > at float.h in:
> >
> > /usr/lib/gcc-lib/i486-linux-gnu/3.3.6/include
> > /usr/lib/gcc/i486-linux-gnu/3.4.6/include
> >
> > and neither one actually defined it.
> >
> > Where is the numerical value held?
>
> All you really need to worry about is that it gets defined when you
> #include <float.h>.
>
> My float.h simply defines DBL_EPSILON to __DBL_EPSILON__. There does not
> appear to be an inclusion of some other file, or a definition of
> __DBL_EPSILON__. So the answer to your question would seem: compiler
> magic. :)
This is very unfortunate. I liked having one file to look at for all my
float constant curiosity.
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