How do I create/detect/handle Infinity?

Contributed by jdporter on Jul 24, 2009 at 18:11 UTC
Q&A > math

Description:

N/T

Answer: How do I create/detect/handle Infinity?
contributed by shmem

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

Answer: How do I create/detect/handle Infinity?
contributed by moritz

I think in Perl 5 this is platform specific, so I'll rather give the Perl 6 answer:

my $num = Inf;
given $num {
    say "+Inf" when Inf;
    say "-Inf" when -Inf;
    say "NaN"  when NaN;
}
[download]

Works in Rakudo today.

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