1Math::PlanePath::WunderUlsiecrhMCeoanntdreirb(u3t)ed PerMlatDho:c:uPmleannteaPtaitohn::WunderlichMeander(3)
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NAME

6       Math::PlanePath::WunderlichMeander -- 3x3 self-similar "R" shape
7

SYNOPSIS

9        use Math::PlanePath::WunderlichMeander;
10        my $path = Math::PlanePath::WunderlichMeander->new;
11        my ($x, $y) = $path->n_to_xy (123);
12

DESCRIPTION

14       This is an integer version of the 3x3 self-similar meander from
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16           Walter Wunderlich, "Uber Peano-Kurven", Elemente der Mathematik,
17           volume 28, number 1, 1973, pages 1-10.
18           <http://sodwana.uni-ak.ac.at/geom/mitarbeiter/wallner/wunderlich/>,
19           <http://sodwana.uni-ak.ac.at/geom/mitarbeiter/wallner/wunderlich/pdf/125.pdf>
20
21             8     20--21--22  29--30--31  38--39--40
22                    |       |   |       |   |       |
23             7     19  24--23  28  33--32  37  42--41
24                    |   |       |   |       |   |
25             6     18  25--26--27  34--35--36  43--44
26                    |                               |
27             5     17  14--13  56--55--54--53--52  45
28                    |   |   |   |               |   |
29             4     16--15  12  57  60--61  50--51  46
30                            |   |   |   |   |       |
31             3      9--10--11  58--59  62  49--48--47
32                    |                   |
33             2      8   5-- 4  65--64--63  74--75--76
34                    |   |   |   |           |       |
35             1      7-- 6   3  66  69--70  73  78--77
36                            |   |   |   |   |   |
37           Y=0->    0-- 1-- 2  67--68  71--72  79--80-...
38
39                   X=0  1   2   3   4   5   6   7   8
40
41       The base pattern is the N=0 to N=8 section.  It works as a traversal of
42       a 3x3 square starting in one corner and going along one side.  The base
43       figure goes upwards and it's then used rotated by 180 degrees and/or
44       transposed to go in other directions,
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46           +----------------+----------------+---------------+
47           | ^              |              * | ^             |
48           | |              |  rotate 180  | | |   base      |
49           | |     8        |       5      | | |     4       |
50           | |   base       |              | | |             |
51           | *              |              v | *             |
52           +----------------+----------------+---------------+
53           | <------------* | <------------* | ^             |
54           |                |                | |             |
55           |       7        |       6        | |     3       |
56           |   rotate 180   |   rotate 180   | |   base      |
57           |  + transpose   |  + transpose   | *             |
58           +----------------+----------------+---------------+
59           |                |                | ^             |
60           |                |                | |             |
61           |       0        |       1        | |     2       |
62           |   transpose    |   transpose    | |   base      |
63           | *----------->  | *------------> | *             |
64           +----------------+----------------+---------------+
65
66       The base 0 to 8 goes upwards, so the across sub-parts are an X,Y
67       transpose.  The transpose in the 0 part means the higher levels go
68       alternately up or across.  So N=0 to N=8 goes up, then the next level
69       N=0,9,18,.,72 goes right, then N=81,162,..,648 up again, etc.
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71       Wunderlich's conception is successive lower levels of detail as a
72       space-filling curve.  The transposing in that case applies to ever
73       smaller parts.  But for the integer version here, the start direction
74       is held fixed and the successively higher levels alternate.  The first
75       move N=0 to N=1 is rightwards per the "Schema" shown in Wunderlich's
76       paper (and like various other "PlanePath" curves).
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FUNCTIONS

79       See "FUNCTIONS" in Math::PlanePath for behaviour common to all path
80       classes.
81
82       "$path = Math::PlanePath::WunderlichMeander->new ()"
83           Create and return a new path object.
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85       "($x,$y) = $path->n_to_xy ($n)"
86           Return the X,Y coordinates of point number $n on the path.  Points
87           begin at 0 and if "$n < 0" then the return is an empty list.
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89       "($n_lo, $n_hi) = $path->rect_to_n_range ($x1,$y1, $x2,$y2)"
90           The returned range is exact, meaning $n_lo and $n_hi are the
91           smallest and biggest in the rectangle.
92
93   Level Methods
94       "($n_lo, $n_hi) = $path->level_to_n_range($level)"
95           Return "(0, 9**$level - 1)".
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SEE ALSO

98       Math::PlanePath, Math::PlanePath::PeanoCurve
99

HOME PAGE

101       <http://user42.tuxfamily.org/math-planepath/index.html>
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LICENSE

104       Copyright 2011, 2012, 2013, 2014, 2015, 2016, 2017, 2018, 2019, 2020
105       Kevin Ryde
106
107       This file is part of Math-PlanePath.
108
109       Math-PlanePath is free software; you can redistribute it and/or modify
110       it under the terms of the GNU General Public License as published by
111       the Free Software Foundation; either version 3, or (at your option) any
112       later version.
113
114       Math-PlanePath is distributed in the hope that it will be useful, but
115       WITHOUT ANY WARRANTY; without even the implied warranty of
116       MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
117       General Public License for more details.
118
119       You should have received a copy of the GNU General Public License along
120       with Math-PlanePath.  If not, see <http://www.gnu.org/licenses/>.
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124perl v5.34.0                      2021-07-M2a2th::PlanePath::WunderlichMeander(3)
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