/usr/share/perl5/Math/PlanePath/DekkingCurve.pm is in libmath-planepath-perl 113-1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
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# This file is part of Math-PlanePath.
#
# Math-PlanePath is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by the
# Free Software Foundation; either version 3, or (at your option) any later
# version.
#
# Math-PlanePath 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. See the GNU General Public License
# for more details.
#
# You should have received a copy of the GNU General Public License along
# with Math-PlanePath. If not, see <http://www.gnu.org/licenses/>.
package Math::PlanePath::DekkingCurve;
use 5.004;
use strict;
#use List::Util 'max';
*max = \&Math::PlanePath::_max;
use vars '$VERSION', '@ISA';
$VERSION = 113;
use Math::PlanePath;
@ISA = ('Math::PlanePath');
use Math::PlanePath::Base::Generic
'is_infinite',
'round_nearest';
use Math::PlanePath::Base::Digits
'round_down_pow',
'digit_split_lowtohigh',
'digit_join_lowtohigh';
# uncomment this to run the ### lines
#use Smart::Comments;
use constant n_start => 0;
use constant class_x_negative => 0;
use constant class_y_negative => 0;
use constant dx_minimum => -1; # NSEW only
use constant dx_maximum => 1;
use constant dy_minimum => -1;
use constant dy_maximum => 1;
use constant dsumxy_minimum => -1;
use constant dsumxy_maximum => 1;
use constant ddiffxy_minimum => -1;
use constant ddiffxy_maximum => 1;
use constant dir_maximum_dxdy => (0,-1); # South
#------------------------------------------------------------------------------
use Math::PlanePath::DekkingCentres;
use vars '@_next_state','@_digit_to_x','@_digit_to_y','@_yx_to_digit';
BEGIN {
*_next_state = \@Math::PlanePath::DekkingCentres::_next_state;
*_digit_to_x = \@Math::PlanePath::DekkingCentres::_digit_to_x;
*_digit_to_y = \@Math::PlanePath::DekkingCentres::_digit_to_y;
*_yx_to_digit = \@Math::PlanePath::DekkingCentres::_yx_to_digit;
}
# tables generated by tools/dekking-curve-table.pl
#
my @edge_dx = (0,0,0,1,1, 0,0,1,1,0, 0,0,0,1,0, 0,0,1,0,1, 0,1,0,1,1,
1,1,1,1,1, 1,1,1,0,1, 1,1,0,1,0, 0,0,1,0,0, 0,1,1,0,0,
1,1,1,0,0, 1,1,0,0,1, 1,1,1,0,1, 1,1,0,1,0, 1,0,1,0,0,
0,0,0,0,0, 0,0,0,1,0, 0,0,1,0,1, 1,1,0,1,1, 1,0,0,1,1,
1,1,1,1,1, 1,0,0,0,0, 1,1,1,1,1, 0,0,0,0,1, 1,0,0,1,1,
1,1,1,0,0, 1,1,1,1,1, 0,0,0,1,1, 0,0,1,0,1, 0,1,0,1,1,
0,0,0,0,0, 0,1,1,1,1, 0,0,0,0,0, 1,1,1,1,0, 0,1,1,0,0,
0,0,0,1,1, 0,0,0,0,0, 1,1,1,0,0, 1,1,0,1,0, 1,0,1,0,0);
my @edge_dy = (0,0,0,0,0, 0,0,0,1,0, 0,0,1,0,1, 1,1,0,1,1, 1,0,0,1,1,
0,0,0,1,1, 0,0,1,1,0, 0,0,0,1,0, 0,0,1,0,1, 0,1,0,1,1,
1,1,1,1,1, 1,1,1,0,1, 1,1,0,1,0, 0,0,1,0,0, 0,1,1,0,0,
1,1,1,0,0, 1,1,0,0,1, 1,1,1,0,1, 1,1,0,1,0, 1,0,1,0,0,
0,0,0,1,1, 0,0,0,0,0, 1,1,1,0,0, 1,1,0,1,0, 1,0,1,0,0,
1,1,1,1,1, 1,0,0,0,0, 1,1,1,1,1, 0,0,0,0,1, 1,0,0,1,1,
1,1,1,0,0, 1,1,1,1,1, 0,0,0,1,1, 0,0,1,0,1, 0,1,0,1,1,
0,0,0,0,0, 0,1,1,1,1, 0,0,0,0,0, 1,1,1,1,0, 0,1,1,0,0);
sub n_to_xy {
my ($self, $n) = @_;
### DekkingCurve n_to_xy(): $n
if ($n < 0) { return; }
if (is_infinite($n)) { return ($n,$n); }
my $int = int($n);
$n -= $int;
my @digits = digit_split_lowtohigh($int,25);
my $state = 0;
my @x;
my @y;
foreach my $i (reverse 0 .. $#digits) {
$state += $digits[$i];
$x[$i] = $_digit_to_x[$state];
$y[$i] = $_digit_to_y[$state];
$state = $_next_state[$state];
}
### @x
### @y
### $state
### dx: $_digit_to_x[$state+24] - $_digit_to_x[$state]
### dy: $_digit_to_y[$state+24] - $_digit_to_y[$state]
my $zero = $int * 0;
return ($n * (($_digit_to_x[$state+24] - $_digit_to_x[$state])/4)
+ digit_join_lowtohigh(\@x, 5, $zero)
+ $edge_dx[$state],
$n * (($_digit_to_y[$state+24] - $_digit_to_y[$state])/4)
+ digit_join_lowtohigh(\@y, 5, $zero)
+ $edge_dy[$state]);
}
sub xy_to_n {
my ($self, $x, $y) = @_;
### DekkingCurve xy_to_n(): "$x, $y"
$x = round_nearest ($x);
$y = round_nearest ($y);
if ($x < 0 || $y < 0) {
return undef;
}
if (is_infinite($x)) {
return $x;
}
if (is_infinite($y)) {
return $y;
}
foreach my $xoffset (0,-1) {
foreach my $yoffset (0,-1) {
my @x = digit_split_lowtohigh($x+$xoffset,5);
my @y = digit_split_lowtohigh($y+$yoffset,5);
my $state = 0;
my @n;
foreach my $i (reverse 0 .. max($#x,$#y)) {
my $digit = $n[$i] = $_yx_to_digit[$state + 5*($y[$i]||0) + ($x[$i]||0)];
$state = $_next_state[$state+$digit];
}
my $n = digit_join_lowtohigh(\@n, 25, $x*0*$y);
my ($nx,$ny) = $self->n_to_xy($n);
if ($nx == $x && $ny == $y) {
return $n;
}
}
}
return undef;
}
# not exact
sub rect_to_n_range {
my ($self, $x1,$y1, $x2,$y2) = @_;
### DekkingCurve rect_to_n_range(): "$x1,$y1, $x2,$y2"
$x1 = round_nearest ($x1);
$x2 = round_nearest ($x2);
$y1 = round_nearest ($y1);
$y2 = round_nearest ($y2);
$x2 = max($x1,$x2);
$y2 = max($y1,$y2);
if ($x2 < 0 || $y2 < 0) {
### rectangle all negative, no N values ...
return (1, 0);
}
my ($pow) = round_down_pow (max($x2,$y2)+1, 5);
### $pow
### $level
return (0, 25*$pow*$pow-1);
}
1;
__END__
=for stopwords eg Ryde ie Math-PlanePath Dekking
=head1 NAME
Math::PlanePath::DekkingCurve -- 5x5 self-similar edge curve
=head1 SYNOPSIS
use Math::PlanePath::DekkingCurve;
my $path = Math::PlanePath::DekkingCurve->new;
my ($x, $y) = $path->n_to_xy (123);
=head1 DESCRIPTION
This is an integer version of a 5x5 self-similar curve by Dekking,
=cut
# math-image --path=DekkingCurve --all --output=numbers_dash --size=78x30
=pod
10 | 123-124-125-... 86--85
| | | |
9 | 115-116-117 122-121 90--89--88--87 84
| | | | | |
8 | 114-113 118-119-120 91--92--93 82--83
| | | |
7 | 112 107-106 103-102 95--94 81 78--77
| | | | | | | | | |
6 | 111 108 105-104 101 96--97 80--79 76
| | | | | |
5 | 110-109 14--15 100--99--98 39--40 75 66--65
| | | | | | | |
4 | 10--11--12--13 16 35--36--37--38 41 74 71--70 67 64
| | | | | | | | | |
3 | 9---8---7 18--17 34--33--32 43--42 73--72 69--68 63
| | | | | |
2 | 5---6 19 22--23 30--31 44 47--48 55--56--57 62--61
| | | | | | | | | | | |
1 | 4---3 20--21 24 29--28 45--46 49 54--53 58--59--60
| | | | | |
Y=0 | 0---1---2 25--26--27 50--51--52
+----------------------------------------------------------------
X=0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
The base pattern is the N=0 to N=25 section. It then repeats with rotations
or reversals which make the ends join. For example N=75 to N=100 is the
base pattern in reverse, ie. from N=25 down to N=0. Or N=50 to N=75 is
reverse and also rotate by -90.
The curve segments are edges of squares in a 5x5 arrangement.
+- - -+- - -+- - 14----15 ---+
| | | | v |> |
^ ^ <| |
10----11----12----13- - 16 --+
| v |> |
|> ^ ^ |
9-----8-----7 -- 18----17 --+
v | | |> |
| ^ |> | ^
+- - 5-----6 - 19 22----23
| <| | <|
| <| ^ | <| |
+- - 4-----3 20----21 -- 24
| v <|
^ ^ |> | | |
0-----1-----2 -- + -- -+- 25
The little notch marks show which square each edge represents. This is the
side the curve expands into at the next level. For example N=1 to N=2 has
its notch on the left so the next level N=25 to N=50 expands on the left.
An expansion on the left is a repeat of the base shape, possibly rotated 90,
180 or 270 degrees. An expansion on the right is the base shape in reverse,
as for example N=2 to N=3 on the right becomes N=50 to N=75 traversing to
the right at the next level.
=head1 FUNCTIONS
See L<Math::PlanePath/FUNCTIONS> for the behaviour common to all path
classes.
=over 4
=item C<$path = Math::PlanePath::DekkingCurve-E<gt>new ()>
Create and return a new path object.
=item C<($x,$y) = $path-E<gt>n_to_xy ($n)>
Return the X,Y coordinates of point number C<$n> on the path. Points begin
at 0 and if C<$n E<lt> 0> then the return is an empty list.
=back
=head1 SEE ALSO
L<Math::PlanePath>,
L<Math::PlanePath::DekkingCentres>,
L<Math::PlanePath::CincoCurve>,
L<Math::PlanePath::PeanoCurve>
=head1 HOME PAGE
L<http://user42.tuxfamily.org/math-planepath/index.html>
=head1 LICENSE
Copyright 2011, 2012, 2013 Kevin Ryde
This file is part of Math-PlanePath.
Math-PlanePath is free software; you can redistribute it and/or modify it
under the terms of the GNU General Public License as published by the Free
Software Foundation; either version 3, or (at your option) any later
version.
Math-PlanePath 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. See the GNU General Public License for
more details.
You should have received a copy of the GNU General Public License along with
Math-PlanePath. If not, see <http://www.gnu.org/licenses/>.
=cut
|