Polynomials and modular arithmetic to get the moral out of this classic Aesop's fable.

If you haven't practiced your Latin recently, an English version is available at Project Gutenberg (search "The Wolf and the Lamb").

#!/usr/bin/perl -w

use strict;

undef $/;
our $data = lc <DATA> . "jkwy" x 10;
$data =~ s/(\015|\012)+/ /g; # Needed to solve newline mismatches
our @letter = split //, $data;

sub poleval {
    my ($x, $r) = (shift, 0);
    $r = ( $r * $x + $_ ) % 683 for @_;
    $r;
}

for my $p ( [504,354,142,50,9],[155,9,370,394,644],[48,38,324,84] ) {
    for my $x ( 0 .. 2 * @$p - 1 ) {
        print $letter[ poleval( $x, @$p) ];
    }
    print "\n";
}

__DATA__
Lupus et agnus
Ad rivum eundem lupus et agnus venerant,
siti compulsi. Superior stabat lupus,
longeque inferior agnus. Tunc fauce improba
latro incitatus iurgii causam intulit;
'Cur' inquit 'turbulentam fecisti mihi
aquam bibenti?' Laniger contra timens
'Qui possum, quaeso, facere quod quereris, lupe?
A te decurrit ad meos haustus liquor'.
Repulsus ille veritatis viribus
'Ante hos sex menses male' ait 'dixisti mihi'.
Respondit agnus 'Equidem natus non eram'.
'Pater hercle tuus' ille inquit 'male dixit mihi';
atque ita correptum lacerat iniusta nece.
Haec propter illos scripta est homines fabula
qui fictis causis innocentes opprimunt.
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Challenge

If you have some time to waste: are you able to get another moral by only changing the polynomial coefficients in the line starting with "for my $p"?

Antonio

The stupider the astronaut, the easier it is to win the trip to Vega - A. Tucket