The algorithm shown in the OP falls under the more generic category of "hashing algorithm" which is unlikely to need reinventing for Perl, whereby I would advocate instead something like:

# more Perlish implementation example (update: simplified)
package UnorderedPair;

use strict;

sub new {
    my $class = shift;
    my $self = bless {};
    @_ and $self -> encode( @_ );
    return $self, $class;
}

sub encode { # x, y, value
    my $self = shift;
    my ( $x, $y ) = NDsc( $_[0], $_[1] );
    $self -> { $x }{ $y } = $_[2];
}

sub decode { # x, y ... return value
    my $self = shift;
    my ( $x, $y ) = NDsc( $_[0], $_[1] );
    return $self -> { $x }{ $y };
}

sub NDsc{ # sort numeric descending
    return sort { $b <=> $a } @_;
}

1;
[download]

---

---

Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!

Titles consisting of a single word are discouraged, and in most cases are disallowed outright.

Read Where should I post X? if you're not absolutely sure you're posting in the right place.

Please read these before you post! —

• How do I compose an effective node title?
• How do I post a question effectively?
• Markup in the Monastery

Posts may use any of the Perl Monks Approved HTML tags:

a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr

You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)

	For:		Use:
	&		&
	<		&lt;
	>		&gt;
	[		&#91;
	]		&#93;

Link using PerlMonks shortcuts! What shortcuts can I use for linking?

See Writeup Formatting Tips and other pages linked from there for more info.