# Copyright 2007, 2009, 2010 Kevin Ryde
# This file is part of Chart.
#
# Chart 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.
#
# Chart 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 Chart. If not, see <http://www.gnu.org/licenses/>.
package App::Chart::Series::Derived::ElderPower;
use 5.010;
use strict;
use warnings;
use Carp;
use List::Util qw(min max);
use Locale::TextDomain ('App-Chart');
use base 'App::Chart::Series::Indicator';
use App::Chart::Series::Derived::EMA;
# http://www.incrediblecharts.com/technical/elder_ray_index.php
# Formula, sample All Ords (yahoo ^AORD) from Aug 2001.
#
# http://www.prophet.net/analyze/popglossary.jsp?studyid=ELDR
# Formula, sample Hilton Hotels (HLT) from 2002/2003, weekly scale.
#
sub longname { __('Elder Bull/Bear Power') }
sub shortname { __('Elder Power') }
sub manual { __p('manual-node','Elder Bull/Bear Power') }
use constant
{ type => 'indicator',
units => 'momentum',
hlines => [ 0 ],
parameter_info => [ { name => __('Days'),
key => 'elder_power_days',
type => 'integer',
minimum => 1,
default => 13 } ],
line_colours => { bull => App::Chart::UP_COLOUR(),
bear => App::Chart::DOWN_COLOUR() },
};
sub new {
my ($class, $parent, $N) = @_;
$N //= parameter_info()->[0]->{'default'};
($N > 0) || croak "ElderPower bad N: $N";
return $class->SUPER::new
(parent => $parent,
parameters => [ $N ],
arrays => { bull => [],
bear => [] },
array_aliases => { values => 'bull' });
}
*warmup_count = \&App::Chart::Series::Derived::EMA::warmup_count;
sub proc {
my ($class_or_self, $N) = @_;
my $ema_proc = App::Chart::Series::Derived::EMA->proc($N);
return sub {
my ($high, $low, $close) = @_;
my $ema = $ema_proc->($close);
$high //= $close;
$low //= $close;
return ($high - $ema, $low - $ema);
};
}
sub fill_part {
my ($self, $lo, $hi) = @_;
my $parent = $self->{'parent'};
my $warmup_count = $self->warmup_count_for_position ($lo);
my $start = $parent->find_before ($lo, $warmup_count);
$parent->fill ($lo, $hi);
my $p = $parent->values_array;
my $ph = $parent->array('highs') || $p;
my $pl = $parent->array('lows') || $p;
my $su = $self->array('bull');
my $sl = $self->array('bear');
$hi = min ($hi, $#$p);
if ($#$su < $hi) { $#$su = $hi; } # pre-extend
if ($#$sl < $hi) { $#$sl = $hi; } # pre-extend
my $proc = $self->proc(@{$self->{'parameters'}});
foreach my $i ($start .. $lo-1) {
my $value = $p->[$i] // next;
$proc->($ph->[$i], $pl->[$i], $value);
}
foreach my $i ($lo .. $hi) {
my $value = $p->[$i] // next;
($su->[$i], $sl->[$i]) = $proc->($ph->[$i], $pl->[$i], $value);
}
}
1;
__END__
# =head1 NAME
#
# App::Chart::Series::Derived::ElderPower -- Elder bull power / bear power
#
# =head1 SYNOPSIS
#
# my $series = $parent->ElderPower($N);
#
# =head1 DESCRIPTION
#
# ...
#
# =head1 SEE ALSO
#
# L<App::Chart::Series>
#
# =cut