#!/usr/local/bin/perl -w

use strict;

use Math::Polynomial;

my %h = ();

my $s = "Just another Perl h";

# put string into a hash {0=>J, 1=>u ...)
map { $h{$_}=ord(substr($s,$_,1))}(0..length($s)-1);

# use the library to get the polynomial factors
my @p = split / /, Math::Polynomial::interpolate(%h);

# generate the calculation string from factors
my $p;
my $i = length($s)-1;
map{ $p .= "+$_*\$i**$i";$i-- } @p;

# tidy the string, remove $i**0 (=1)
# add .5 to total for rounding purposes
$p =~ s/\+\-/\-/g;
$p =~ s/.*\(//;
$p =~ s/\).*/.5/;
print "$p\n";

# test the equation
for $i (0..length($s)-1) {
	print chr eval $p;
}