#!/usr/bin/perl -w
# Copyright 2011, 2012 Kevin Ryde
# This file is part of Math-NumSeq.
#
# Math-NumSeq 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-NumSeq 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-NumSeq. If not, see <http://www.gnu.org/licenses/>.
require 5;
use strict;
# uncomment this to run the ### lines
#use Smart::Comments;
{
# delta
require Math::PlanePath::SquareSpiral;
my $path = Math::PlanePath::SquareSpiral->new;
require Math::NumSeq::SpiroFibonacci;
my $seq = Math::NumSeq::SpiroFibonacci->new;
$seq->next;
$seq->next;
foreach (1 .. 200) {
my $queue = $seq->{'queue'};
my $queuelen = scalar(@$queue);
my ($n, $value) = $seq->next;
my $pn = n_to_closest($path,$n);
my ($dx,$dy) = n_to_dxdy($path,$n-1);
my $dir = dxdy_to_dir($dx,$dy);
my $diff = $n - $pn;
my $xx = ($queuelen != $diff ? ' ***' : '');
printf "%3d dir=%d %3d %2d %2d%s\n",
$n, $dir, $pn, $diff, $queuelen, $xx;
}
exit 0;
}
sub n_to_dxdy {
my ($path, $n) = @_;
my ($x,$y) = $path->n_to_xy($n);
my ($next_x,$next_y) = $path->n_to_xy($n+1);
return ($next_x - $x,
$next_y - $y);
}
# with Y reckoned increasing upwards
sub dxdy_to_dir {
my ($dx, $dy) = @_;
if ($dx > 0) { return 0; } # east
if ($dx < 0) { return 2; } # west
if ($dy > 0) { return 1; } # north
if ($dy < 0) { return 3; } # south
die "oops unrecognised $dx,$dy";
}
sub n_to_closest {
my ($path, $n) = @_;
my ($x,$y) = $path->n_to_xy($n);
my $pn = 0;
foreach my $dxdy ([0,1],[0,-1],
[1,0],[-1,0]) {
my ($dx,$dy) = @$dxdy;
my $dn = $path->xy_to_n($x+$dx,$y+$dy);
### straight: $dn
if ($dn < $n-1 && $dn > $pn) {
### straight at: "i=$n,x=$x,y=$y dx=$dx dy=$dy pn=$dn"
$pn = $dn;
}
}
if (! $pn) {
foreach my $dxdy ([1,1],[1,-1],
[-1,1],[-1,-1]) {
my ($dx,$dy) = @$dxdy;
my $dn = $path->xy_to_n($x+$dx,$y+$dy);
### diag: $dn
if ($dn < $n-1 && $dn > $pn) {
### diagonal at: "i=$n,x=$x,y=$y dx=$dx dy=$dy pn=$dn"
$pn = $dn;
}
}
}
if (! $pn) {
die "oops, not found for n=$n";
}
return $pn;
}