Sisyphus wrote:
But on the 2 machines I ran that code on (linux and Win32), IEEE NaN is not
supported - as evidenced by the fact that NaN + 1 == 1.
NaN is supported on both of those platforms (AFAIK), but the string "NaN" is not
a canonical way to generate the special IEEE NaN number.
I also checked by
running (as suggested in perlop):
perl -le '$a = NaN; print "No NaN support here" if $a == $a'
I don't see support for that construct in the code at all (there is special INF
and NaN handling in numeric.c:Perl_grok_number but this only bypasses the
warning and doesn't affect the math), so I'm not sure that was ever anything
more than wishful thinking. I think the thought was that there would be special
handling so that this:
$x = NaN; # note bareword not string
would autogenerate an actual NaN number, but it doesn't exist (AFAICT) in toke.c
where it belongs.
However, Tels did add this support to bigint:
use bigint;
$x = NaN;
$x += 1;
$y = "foo";
$y += 1;
print $x, " ", $y, "\n";
__END__
produces the expected (or not in the second case):
NaN NaN
HTH
John
--
John Peacock
Director of Information Research and Technology
Rowman & Littlefield Publishing Group
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