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Postings from June 2001
On Wed, Jun 27, 2001 at 04:24:01PM +0100, Mike Guy wrote:
> Nicholas Clark <nick@ccl4.org> wrote
> > On Mon, Jun 25, 2001 at 05:27:44PM -0500, Jarkko Hietaniemi wrote:
> > > NV = 4745162525730
> > > NV = 4745162525730
> >
> > This is crazy. They appear to be the same.
>
> Not necessarily. Sneaky stuff, float-to-string conversion. Watch:
> If you want to know reliably the value of an NV, you have to look at more
> that its printed form. If you know a quantity which is near to the
> expected value, and which is exactly representable, the simplest
> trick is to display the difference from that quantity, e.g.
> displaying $y-4745162525730 in the above example.
Good point. What does the nasty AIX configuration make of:
#!/usr/bin/perl -w
$x = 4745162525730;
$y = int(279964589018079/59);
if ($y == $x) {
print "ok 13\n"
} else {
print "not ok 13 # int(279964589018079/59) is $y, not $x\n";
}
use Devel::Peek;
Dump($x);
Dump($y);
Dump($y-4745162525730);
#!/usr/bin/perl -w
$x = 4745162525730;
$y = int(279964589018079/59);
if ($x == $y) {
print "ok 13\n"
} else {
print "not ok 13 # int(279964589018079/59) is $y, not $x\n";
}
use Devel::Peek;
Dump($x);
Dump($y);
Dump($y-4745162525730);
I get 0 for the last dumps
Nicholas Clark
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