# MATH::PLANEPATH::GOSPERREPLICATE(3PM) - man page online | library functions

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2016-01-11

Math::PlanePath::GosperReplicatUsermContributed Perl DocumenMath::PlanePath::GosperReplicate(3pm)## NAME

Math::PlanePath::GosperReplicate -- self-similar hexagon replications## SYNOPSIS

use Math::PlanePath::GosperReplicate; my $path = Math::PlanePath::GosperReplicate->new; my ($x, $y) = $path->n_to_xy (123);## DESCRIPTION

This is a self-similar hexagonal tiling of the plane. At each level the shape is the Gosper island. 17----16 4 / \ 24----23 18 14----15 3 / \ \ 25 21----22 19----20 10---- 9 2 \ / \ 26----27 3---- 2 11 7---- 8 1 / \ \ 31----30 4 0---- 1 12----13 <- Y=0 / \ \ 32 28----29 5---- 6 45----44 -1 \ / \ 33----34 38----37 46 42----43 -2 / \ \ 39 35----36 47----48 -3 \ 40----41 -4 ^ -7 -6 -5 -4 -3 -2 -1 X=0 1 2 3 4 5 6 7 The points are spread out on every second X coordinate to make a a triangular lattice in integer coordinates (see "Triangular Lattice" in Math::PlanePath). The base pattern is the inner N=0 to N=6, then six copies of that shape are arranged around as the blocks N=7,14,21,28,35,42. Then six copies of the resulting N=0 to N=48 shape are replicated around, etc. Each point represents a little hexagon, thus tiling the plane with hexagons. The innermost N=0 to N=6 are for instance, * * / \ / \ / \ / \ * * * | 3 | 2 | * * * / \ / \ / \ / \ / \ / \ * * * * | 4 | 0 | 1 | * * * * \ / \ / \ / \ / \ / \ / * * * | 5 | 6 | * * * \ / \ / \ / \ / * * The further replications are the same arrangement, but the sides become ever wigglier and the centres rotate around. The rotation can be seen at N=7 X=5,Y=1 which is up from the X axis. The "FlowsnakeCentres" path is this same replicating shape, but starting from a side instead of the middle and traversing in such as way as to make each N adjacent. The "Flowsnake" curve itself is this replication too, but following edges. Complex Base The path corresponds to expressing complex integers X+i*Y in a base b = 5/2 + i*sqrt(3)/2 with some scaling to put equilateral triangles on a square grid. So for integer X,Y with X and Y either both odd or both even, X/2 + i*Y*sqrt(3)/2 = a[n]*b^n + ... + a[2]*b^2 + a[1]*b + a[0] where each digit a[i] is either 0 or a sixth root of unity encoded into N as base 7 digits, r = e^(i*pi/3) = 1/2 + i*sqrt(3)/2 sixth root of unity N digit a[i] complex number ------- ------------------- 0 0 1 r^0 = 1 2 r^2 = 1/2 + i*sqrt(3)/2 3 r^3 = -1/2 + i*sqrt(3)/2 4 r^4 = -1 5 r^5 = -1/2 - i*sqrt(3)/2 6 r^6 = 1/2 - i*sqrt(3)/2 7 digits suffice because norm(b) = (5/2)^2 + (sqrt(3)/2)^2 = 7## FUNCTIONS

See "FUNCTIONS" in Math::PlanePath for behaviour common to all path classes. "$path = Math::PlanePath::GosperReplicate->new ()" Create and return a new path object. "($x,$y) = $path->n_to_xy ($n)" Return the X,Y coordinates of point number $n on the path. Points begin at 0 and if "$n < 0" then the return is an empty list. Level Methods "($n_lo, $n_hi) = $path->level_to_n_range($level)" Return "(0, 7**$level - 1)".## SEE ALSO

Math::PlanePath, Math::PlanePath::GosperIslands, Math::PlanePath::Flowsnake, Math::PlanePath::FlowsnakeCentres, Math::PlanePath::QuintetReplicate, Math::PlanePath::ComplexPlus## HOME PAGE

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

Copyright 2011, 2012, 2013, 2014, 2015 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/>.perl v5.22.1 2016-01-11 Math::PlanePath::GosperReplicate(3pm)

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Math::PlanePath::GosperReplicate(3pm) | referred by | |

refer to | sqrt(3) |