Hi Ben,
Paul Eggert wrote:
> > * Is it acceptable for isfinite to raise an exception on
> > a signaling NaN?
>
> Yes.
I disagree. We know what the relevant standards say: [1]
Also there is the issue with numbers outside the IEEE spec: [2]
Since this is a classification function, IMO it must not raise an exception,
since this function is often used like this:
double foo (double x)
{
if (!isfinite (x))
return x;
...
}
Since the only function in gnulib so far that can reliably sort out
signalling NaNs and non-IEEE numbers without exception is isnan*(), IMO
gl_isfinite* needs to use this function. Like this:
int gl_isfinitef (float x)
{
return !isnanf (x) && (x + x == x || x == 0.0f);
}
Or, using Paul's idea:
int gl_isfinitef (float x)
{
return !isnanf (x) && (x - x == 0.0f);
}
Bruno
[1] http://lists.gnu.org/archive/html/bug-gnulib/2007-03/msg00396.html
[2] http://lists.gnu.org/archive/html/bug-gnulib/2007-06/msg00040.html
