Kahan summation: Difference between revisions

=={{header|Perl}}==

{{trans|Perl 6}}

<lang perl>use strict;

use warnings;

use feature 'say';

sub kahan {

my(@nums) = @_;

my $summ = my $c = 0e0;

for my $num (@nums) {

my $y = $num - $c;

my $t = $summ + $y;

$c = ($t - $summ) - $y;

$summ = $t;

}

$summ

}

my $eps = 1;

do { $eps /= 2 } until 1e0 == 1e0 + $eps;

say 'Epsilon: ' . $eps;

say 'Simple sum: ' . sprintf "%.16f", ((1e0 + $eps) - $eps);

say 'Kahan sum: ' . sprintf "%.16f", kahan(1e0, $eps, -$eps);</lang>

{{out}}

<pre>Epsilon: 1.11022302462516e-16

Simple sum: 0.9999999999999999

Kahan sum: 1.0000000000000000</pre>