File Coverage

blib/lib/Math/NumSeq/BaumSweet.pm

Criterion	Covered	Total	%
statement	46	47	97.8
branch	5	6	83.3
condition	2	3	66.6
subroutine	13	13	100.0
pod	2	2	100.0
total	68	71	95.7

# Copyright 2011, 2012, 2013, 2014 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 .


# math-image --values=BaumSweet --path=ZOrderCurve
#
# radix parameter ?


package Math::NumSeq::BaumSweet;
use 5.004;
use strict;

use vars '$VERSION','@ISA';
$VERSION = 72;

use Math::NumSeq;
use Math::NumSeq::Base::IterateIth;
@ISA = ('Math::NumSeq::Base::IterateIth',
        'Math::NumSeq');
*_is_infinite = \&Math::NumSeq::_is_infinite;

# uncomment this to run the ### lines
#use Smart::Comments;

# use constant name => Math::NumSeq::__('Baum-Sweet');
use constant description => Math::NumSeq::__('Baum-Sweet sequence, 1 if i contains no odd-length run of 0-bits, 0 if it does.');
use constant default_i_start => 0;
use constant values_min => 0;
use constant values_max => 1;
use constant characteristic_integer => 1;

# cf A037011 "Baum Sweet cubic"
#            a(k)=1 iff k/3 is in A003714 fibbinary
#
use constant oeis_anum => 'A086747'; # starting OFFSET=0 value 1

sub ith {
  my ($self, $i) = @_;
  ### BaumSweet ith(): $i

  if (_is_infinite($i)) {
    return $i;
  }
  while ($i >= 1) {
    if (($i % 2) == 0) {
      my $oddzeros = 0;
      do {
        $oddzeros ^= 1;
        $i /= 2;
      } until ($i % 2);
      if ($oddzeros) {
        return 0;
      }
    }
    $i = int($i/2);
  }
  return 1;
}

sub pred {
  my ($self, $value) = @_;
  return ($value == 0 || $value == 1);
}

1;
__END__