Answer: How do I create/detect/handle Infinity?

Creating Inf/NaN:

use Devel::Peek;
$inf = (~@~)**(~@~);
$nan = $inf / $inf;
Dump $_ for $inf, $nan;
__END__
SV = NV(0x9e15f84) at 0x9dfc11c
  REFCNT = 2
  FLAGS = (NOK,pNOK)
  NV = inf
SV = NV(0x9e15f9c) at 0x9dfc59c
  REFCNT = 2
  FLAGS = (NOK,pNOK)
  NV = nan
[download]

Detecting Inf/NaN: since they are numeric values, Inf and NaN can be tested for with the numeric equality/inequality operators == and !=. For Inf, greater and less also work.

Handling: not useful ;-)

Devel::Peek

Replies are listed 'Best First'.
Re: Answer: How do I create/detect/handle Infinity? by ysth (Canon) on Jul 26, 2009 at 06:26 UTC
NaN doesn't test as == anything, even another NaN. -- Online Fortune Cookie Search Office Space merchandise	[reply]
Re^2: Answer: How do I create/detect/handle Infinity? by syphilis (Bishop) on Jul 26, 2009 at 08:41 UTC
NaN doesn't test as == anything, even another NaN. I was wondering: `unless ($x <= $inf) { print "\$x is definitely a NaN\n" } else { print "\$x is definitely NOT a NaN\n" }` [download] Is that reliable ? ... assuming, of course, that $inf is in fact + infinity, and that there are no bugs present. Seems to me that ought to be good enough. Cheers, Rob	[reply] [d/l]
Re^3: Answer: How do I create/detect/handle Infinity? by ysth (Canon) on Jul 26, 2009 at 10:12 UTC
Yes. Other ways: `$isnan = ($x != $x); $isnan = ! defined($x <=> 0);` [download] -- Online Fortune Cookie Search Office Space merchandise	[reply] [d/l]
Re^4: Answer: How do I create/detect/handle Infinity? by syphilis (Bishop) on Jul 26, 2009 at 12:07 UTC
Re^5: Answer: How do I create/detect/handle Infinity? by ysth (Canon) on Jul 26, 2009 at 20:32 UTC


Pathologically Eclectic Rubbish Lister
	PerlMonks