# N_low
# N_high
# N_middle
# position_offset
#
# 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::PrimeFactorExtract;
use 5.004;
use strict;
use List::Util qw(min max sum reduce);
use Math::Factor::XS 0.39 'prime_factors'; # version 0.39 for prime_factors()
use vars '$VERSION', '@ISA';
$VERSION = 69;
use Math::NumSeq;
use Math::NumSeq::Base::IterateIth;
@ISA = ('Math::NumSeq::Base::IterateIth',
'Math::NumSeq');
use Math::NumSeq 7; # v.7 for _is_infinite()
*_is_infinite = \&Math::NumSeq::_is_infinite;
# uncomment this to run the ### lines
#use Smart::Comments;
# use constant name => Math::NumSeq::__('...');
use constant description => Math::NumSeq::__('Extract prime factor from i.');
use constant default_i_start => 1;
use constant characteristic_increasing => 0;
use constant parameter_info_array =>
[
{
name => 'extract_type',
type => 'enum',
default => 'minimum',
choices => ['minimum','maximum',
'mean',
# 'median',
'quadratic_mean','geometric_mean',
],
},
{
name => 'on_values',
type => 'enum',
default => 'all',
choices => ['all','composites',
],
},
];
sub values_min {
my ($self) = @_;
# if ($self->{'extract_type'} eq 'high') {
# return ($self->i_start > 0 ? 1 : 0);
# }
return 1;
}
my %type_is_integer = (low => 1,
high => 1,
second_low => 1,
second_high => 1,
middle => 1,
minimum => 1,
maximum => 1,
mean => 0,
median => 0,
mode => 0,
geometric_mean => 0,
quadratic_mean => 0,
);
sub characteristic_integer {
my ($self) = @_;
return $type_is_integer{$self->{'extract_type'}};
}
#------------------------------------------------------------------------------
# cf A118663 prime index of least prime dividing the composites
my %oeis_anum;
$oeis_anum{'all'}->{'minimum'} = 'A020639';
# OEIS-Catalogue: A020639 extract_type=min
sub oeis_anum {
my ($self) = @_;
return $oeis_anum{$self->{'on_values'}}->{$self->{'extract_type'}};
}
#------------------------------------------------------------------------------
sub rewind {
my ($self) = @_;
$self->{'i'} = $self->i_start;
if ($self->{'on_values'} eq 'composites') {
require Math::NumSeq::Primes;
my $seq = $self->{'primes_seq'} = Math::NumSeq::Primes->new;
$self->{'upto'} = 0;
$self->{'next_prime'} = 0;
}
}
sub next {
my ($self) = @_;
### PrimeFactorExtract next(): $self->{'i'}
my $i = $self->{'i'}++;
my $value;
if ($self->{'on_values'} eq 'composites') {
until (($value = $self->{'upto'}++) < $self->{'next_prime'}) {
(undef, $self->{'next_prime'}) = $self->{'primes_seq'}->next;
}
} else {
$value = $i;
}
### $value
my @primes = prime_factors($value)
or return ($i, $value); # value=0 or 1 no factors
### @primes
my $extract_type = $self->{'extract_type'};
if ($extract_type eq 'minimum') {
$value = min(@primes);
} elsif ($extract_type eq 'maximum') {
$value = max(@primes);
} elsif ($extract_type eq 'mean') {
$value = sum(@primes)/scalar(@primes);
} elsif ($extract_type eq 'median') {
# 6 digits 0,1,2,3,4,5 int(6/2)=3 is up
# 6 digits 0,1,2,3,4,5 int((6-1)/2)=2 is down
# 7 digits 0,1,2,3,4,5,6 int(7/2)=3
# 7 digits 0,1,2,3,4,5,6 int((7-1)/2)=3 too
@primes = sort {$a<=>$b} @primes;
# mean if even
$value = ($primes[$#primes/2] + $primes[scalar(@primes)/2]) / 2;
# $value = $primes[$#primes/2]; # round down
} elsif ($extract_type eq 'quadratic_mean') {
$value = sqrt(sum(map{$_*$_}@primes)/scalar(@primes));
} elsif ($extract_type eq 'geometric_mean') {
$value = (reduce {$a*$b} @primes) ** (1/scalar(@primes));
}
return ($i, $value);
# if ($self->{'round'} eq 'up') {
# return $primes[scalar(@primes)/2];
# }
# if ($self->{'round'} eq 'down') {
# }
# return ($primes[$#primes/2] + $primes[scalar(@primes)/2]) / 2;
# if ($extract_type eq 'middle') {
# if ($self->{'round'} eq 'up') {
# return $primes[scalar(@primes)/2];
# }
# if ($self->{'round'} eq 'down') {
# return $primes[$#primes/2];
# }
# }
# if ($extract_type eq 'mode') {
# my @count;
# my $max_count = 0;
# foreach my $digit (@primes) {
# if (++$count[$digit] > $max_count) {
# $max_count = $count[$digit];
# }
# }
# my $sum = 0;
# my $sumcount = 0;
# my $last = 0;
# foreach my $digit (0 .. $#count) {
# if (($count[$digit]||0) == $max_count) {
# if ($self->{'round'} eq 'down') {
# return $digit;
# }
# $sum += $digit; $sumcount++;
# $last = $digit;
# }
# }
# if ($self->{'round'} eq 'up') {
# return $last;
# }
# return $sum/$sumcount;
# }
#
# my $ret;
# if ($extract_type eq 'mean') {
# $ret = List::Util::sum(@primes) / scalar(@primes);
#
# } else {
# die "Unrecognised extract_type: ",$extract_type;
# }
#
# if ($self->{'round'} eq 'down') {
# return int($ret);
# }
# if ($self->{'round'} eq 'up') {
# my $int = int($ret);
# return $int + ($ret != int($ret));
# }
# return $ret;
}
1;
__END__
=for stopwords Ryde Math-NumSeq
=head1 NAME
Math::NumSeq::PrimeFactorExtract -- prime factor extracted from integers
=head1 SYNOPSIS
use Math::NumSeq::PrimeFactorExtract;
my $seq = Math::NumSeq::PrimeFactorExtract->new (extract_type => 'minimum');
my ($i, $value) = $seq->next;
=head1 DESCRIPTION
I<In progress ...>
Extract one of the prime factors from i. C<extract_type> (a string) can be
"minimum" smallest prime factor
"maximum" largest prime factor
"mean" average prime factor
=head1 FUNCTIONS
See L<Math::NumSeq/FUNCTIONS> for the behaviour common to all path classes.
=over 4
=item C<$seq = Math::NumSeq::PrimeFactorExtract-E<gt>new (extract_type =E<gt> $str)>
Create and return a new sequence object.
=back
=head1 SEE ALSO
L<Math::NumSeq>,
L<Math::NumSeq::PrimeFactorCount>
=head1 HOME PAGE
L<http://user42.tuxfamily.org/math-numseq/index.html>
=head1 LICENSE
Copyright 2012, 2013, 2014 Kevin Ryde
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/>.
=cut