#!/usr/bin/env perl

use 5.022;
use strict;
use warnings;
use Math::DifferenceSet::Planar;

$| = 1;

die "usage: pds_zeta [file]...\n" if @ARGV && $ARGV[0] =~ /^-[^-]/s;

my $delta = shift @ARGV;

while (<<>>) {
    s/^\s+//;
    my @e = split /\s+/;
    next if !@e;

    die "integer numbers separated by whitespace expected\n"
        if grep { !/^(?:0|[1-9][0-9]*)\z/ } @e;

    my $s = Math::DifferenceSet::Planar->from_elements(@e);

    my $zeta = $s->zeta;

    print "$zeta\n";
}

__END__
=head1 NAME

pds_zeta - display zeta values of planar difference sets

=head1 SYNOPSIS

  pds_zeta [file]...

=head1 DESCRIPTION

This example program reads planar difference sets, one per line,
as integer numbers separated by whitespace, calculates the zeta
value of each set, and writes these values to standard output.
Cf. L<Math::DifferenceSet::Planar> for the definition of I<zeta>.

The program will fail with an error message if an input line is not a
planar difference set.

=head1 AUTHOR

Martin Becker, E<lt>becker-cpan-mp I<at> cozap.comE<gt>

=head1 COPYRIGHT AND LICENSE

Copyright (c) 2022 by Martin Becker, Blaubeuren.

This library is free software; you can distribute it and/or modify it
under the terms of the Artistic License 2.0 (see the LICENSE file).

=head1 DISCLAIMER OF WARRANTY

This library is distributed in the hope that it will be useful, but
without any warranty; without even the implied warranty of merchantability
or fitness for a particular purpose.

=cut
