# Copyright 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 <http://www.gnu.org/licenses/>.
package Math::NumSeq::AbsCubicDiff;
use 5.004;
use strict;
use vars '$VERSION', '@ISA';
$VERSION = 72;
use Math::NumSeq;
use List::Util 'min';
@ISA = ('Math::NumSeq');
*_is_infinite = \&Math::NumSeq::_is_infinite;
# uncomment this to run the ### lines
#use Smart::Comments;
# use constant name => Math::NumSeq::__('...');
# use constant description => Math::NumSeq::__('S(i) = abs(S(i-1) - S(i-2) - S(i-3))');
use constant i_start => 1;
use constant characteristic_smaller => 1;
use constant characteristic_integer => 1;
use constant parameter_info_array =>
[
{
name => 'initial_values',
type => 'string',
share_key => 'integer_triple',
default => '1,1,2',
width => 8,
# description => Math::NumSeq::__('...'),
},
];
sub values_min {
my ($self) = @_;
return 0; # always 0 ?
# return gcd(_initial_values($self));
}
my %oeis_anum = ('1,1,2' => 'A080096',
'1,1,6' => 'A079624',
'1,1,4' => 'A079623',
'0,0,1' => 'A088226',
);
sub oeis_anum {
my ($self) = @_;
return $oeis_anum{join(',',_initial_values($self))};
}
sub _initial_values {
my ($self) = @_;
my ($f0, $f1, $f2)
= grep {$_ ne ''} split /\D/, $self->{'initial_values'}, 3;
return ($f0||0, $f1||0, $f2||0);
}
sub rewind {
my ($self) = @_;
$self->{'i'} = $self->i_start;
($self->{'f0'},
$self->{'f1'},
$self->{'f2'}) = _initial_values($self);
}
sub next {
my ($self) = @_;
### AbsCubicDiff next(): "i=$self->{'i'} $self->{'f0'} $self->{'f1'} $self->{'f2'}"
(my $ret,
$self->{'f0'},
$self->{'f1'},
$self->{'f2'})
= ($self->{'f0'},
$self->{'f1'},
$self->{'f2'},
abs($self->{'f2'} - $self->{'f1'} - $self->{'f0'}));
### ret: "$ret"
return ($self->{'i'}++, $ret);
}
1;
__END__