Category: 
Fun stuff 
Author/Contact Info 
Juerd

Description: 
This module creates magic squares. A magic square is a square in which
all numbers are differet and the sums of all rows, all columns and the
two diagonals are equal.
(To be uploaded to CPAN soon)

package Math::MagicSquare::Generator;
use strict;
use Carp;
use vars qw($VERSION);
$VERSION = '0.01';
sub _sum {
my $sum = 0;
$sum += $_ for @_;
return $sum
}
sub new {
my ($class, %opt) = @_;
$opt{size} = 5;
$opt{start} = 1;
$opt{step} = 1;
croak "Size needs to be a positive, odd integer"
unless $opt{size} > 0 and
$opt{size} % 2 and
$opt{size} == int($opt{size});
my $self = [
map {
[ (undef) x $opt{size} ]
} 1..$opt{size}
];
my $value = $opt{start};
my $halv = int(@$self / 2);
for my $start_x ($halv..$halv) {
my $x = $start_x  1;
my $y = $x + @$self + 1;
for (1 .. @$self) {
$x = $x  @$self if ++$x > $#$self;
$y = $y  @$self if $y > $#$self;
$self>[$y][$x] = $value;
$value += $opt{step};
}
}
return bless $self, $class;
}
sub hflip {
my ($self) = @_;
my $clone;
push @$clone, [ reverse @$_ ] for @$self;
return bless $clone, ref $self;
}
sub vflip {
my ($self) = @_;
my $clone;
push @$clone, [ @$_ ] for reverse @$self;
return bless $clone, ref $self;
}
sub sum {
my ($self) = @_;
return _sum( @{ $self>[0] } );
}
sub check {
my ($self) = @_;
my $sum = $self>sum;
# Horizontals
for (@$self[1..$#$self]) {
return undef if @$_ > @$self; # undef if not square
return undef if _sum(@$_) != $sum;
}
# Verticals
for my $x (0..$#$self) {
return undef if _sum(map $self>[$_][$x], 0..$#$self) != $sum;
}
# Diagonals
return undef if _sum(map $self>[$_][$_], 0..$#$self) !=
+ $sum;
return undef if _sum(map $self>[$#$self  $_][$_], 0..$#$self) !=
+ $sum;
# Duplicates
my %seen;
$seen{$_}++ for map @$_, @$self;
return undef if _sum(values %seen) != keys %seen;
# Passed all tests!
return $sum;
}
sub as_string {
my ($self) = @_;
my $max = 0;
length > $max and $max = length for map @$_, @$self;
return map { join(' ', map {' 'x($max  length) . $_} @$_) . "\n"
+} @$self;
}
sub as_html {
my ($self) = @_;
return "<table>\n" . join("\n",
map { '<tr><td>' . join('</td><td>', @$_) . '</td></tr>' } @$s
+elf) .
"\n</table>\n";
}
sub as_csv {
my ($self) = @_;
return join("\n", map { join ',', @$_ } @$self) . "\n";
}
1;
__END__
=head1 NAME
Math::MagicSquare::Generator  Magic Square Generator
=head1 SYNOPSIS
use Math::MagicSquare::Generator
my $square = Math::MagicSquare::Generator>new(size => 5,
step => 3,
start=> 6);
for ($square, $square>vflip, $square>hflip) {
print $_>as_string;
print "\n";
}
$square>[0][0] = 15; # Break magic :)
print $square>check ? "Magic square\n" : "Just a square\n";
print '<html><body>';
print Math::MagicSquare::Generator>new>hflip>vflip>as_html;
print '</body></html>';
=head1 DESCRIPTION
This module creates magic squares. A magic square is a square in which
all numbers are different and the sums of all rows, all columns and
the two diagonals are equal.
Math::MagicSquare::Generator cannot create panmagic squares, or square
+s
that have an even size. (A panmagic square is magic square where the
"wrapped" diagonals are also equal.)
=head1 EXAMPLE
3 16 9 22 15 This square is the output of
20 8 21 14 2 print Math::MagicSquare::Generator>new>as_string
+;
7 25 13 1 19
24 12 5 18 6
11 4 17 10 23
The sums of the rows are 65.
The sums of the columns are 65.
The sums of the diagonals are 65.
=head1 METHODS
=over 10
=item new
The constructor that generates the square immediately. It
creates an object using the given named arguments. Valid arguments are
C<size>, C<step> and C<start>. C<size> has to be positive, odd and
integer.
=item check
A checker  returns the common sum if the square is magic, or undef if
it's not. Because the sum can never be 0, you can use this as a boolea
+n
value. (Well, the sum in a 1x1 square can be 0, if the single number i
+s
0.) You can use this method to check if the square has been tampered w
+ith.
=item sum
Returns the common sum of the rows, columns and diagonals.
=item vflip, hflip
These methods return a vertically or horizontally flipped clone of the
square. The clone is a Math::MagicSquare::Generator, so stacking these
methods is possible.
=item as_string, as_html, as_csv
DWYM  return the square as a formatted string, piece of html or in
CSV format.
=back
=head1 THIS MODULE AND Math::MagicSquare
Math::MagicSquare is a module that checks if a square is magical. It
takes a list in its C<new> method, so you'll have to dereference the
generated square:
use Math::MagicSquare;
use Math::MagicSquare::Generator;
my $square = Math::MagicSquare::Generator>new;
print Math::MagicSquare>new( @$square )>check, "\n"; # 2
Its C<check> will always return 2 for squares generated using this
module (or 3 if it's a 1x1 square.
=head1 KNOWN BUGS
None yet.
=head1 AUTHOR
Juerd <juerd@juerd.nl>
=cut

Re: Math::MagicSquare::Generator by merlyn (Sage) on Jan 27, 2002 at 21:34 UTC 
(To be uploaded to CPAN soon)
Did you miss Math::MagicSquare, already in the cpan? How is yours different? Can you just send patches to the original author or take it over instead? I don't see why we need two Magic Square generators in the CPAN!
 Randal L. Schwartz, Perl hacker
Update: Argh. I could swear that when I first looked at Math::MagicSquare,
that it was both a generator and a checker, because I noted it for potential material
for a column. My mistake.
 [reply] 

I made Math::MagicSquare::Generator last night, just because I couldn't sleep and couldn't stop thinking about magic squares. Years ago, we had an assignment at school to create a simple 3x3 magic square. That hounted me for weeks. After several weeks, I gave my teacher a piece of paper with an 11x11 magic square and he was impressed. Last night, I created a 5x5 magic square in my head, with no paper. While doing that, I realised I was thinking in terms of Perl code. I then wrote a module called Math::MagicSquare (on my laptop  no Internet connection (yes, the same laptop that has a 802.11b connection, but the Internet connection was down :)) in one go. The next morning, I checked CPAN to see if there already was a module. And there was  Just like you did, I thought it could generate and check, and I was kind of disappointed that I had reinvented a wheel. Its source was a mess, so I decided to not read, but use the code. Reading the documentation gave me the answer: it was just a checker. I chose to name my module after what it does, hoping the difference would be obvious  I renamed it to Math::MagicSquare::Generator, added documentation and uploaded it to CPAN after checking thoroughly if a module already existed.
We both made the same mistake, and perhaps Math::MagicSquare::Checker would have been a better name for the existing Math::MagicSquare module, but it's too late for that now.
2;0 juerd@ouranos:~$ perl e'undef christmas'
Segmentation fault
2;139 juerd@ouranos:~$
 [reply] [d/l] 
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