File Coverage

blib/lib/Math/ModInt/GF3.pm

Criterion	Covered	Total	%
statement	30	30	100.0
branch	4	4	100.0
condition			n/a
subroutine	17	17	100.0
pod	3	3	100.0
total	54	54	100.0

# Copyright (c) 2012-2019 Martin Becker, Blaubeuren.
# This package is free software; you can distribute it and/or modify it
# under the terms of the Artistic License 2.0 (see LICENSE file).

package Math::ModInt::GF3;

use 5.006;
use strict;
use warnings;

# ----- object definition -----

# Math::ModInt::GF3=ARRAY(...)

# .......... index ..........   # .......... value ..........
use constant F_RESIDUE => 0;    # residue r, 0 .. 2
use constant NFIELDS   => 1;

# ----- class data -----

BEGIN {
    require Math::ModInt;
    our @ISA     = qw(Math::ModInt);
    our $VERSION = '0.012';
}

my @base = map { bless [$_] } 0..2;     # singletons
my @sgn  = (0, 1, -1);
my @neg  = @base[0, 2, 1];
my @add  = (\@base,           [@base[1, 2, 0]], [@base[2, 0, 1]]);
my @sub  = (\@neg,            [@base[1, 0, 2]], [@base[2, 1, 0]]);
my @mul  = ([@base[0, 0, 0]], \@base,           \@neg           );
my @pow  = (
    sub { $_[0] < 0? Math::ModInt->undefined: $base[!$_[0]] },
    sub { $base[            1] },
    sub { $base[$_[0] % 2 + 1] },
);

*centered_residue = \&signed_residue;

# ----- private methods -----

sub _NEG { $neg[$_[0]->[F_RESIDUE]] }
sub _ADD { $add[$_[0]->[F_RESIDUE]]->[$_[1]->[F_RESIDUE]] }
sub _SUB { $sub[$_[0]->[F_RESIDUE]]->[$_[1]->[F_RESIDUE]] }
sub _MUL { $mul[$_[0]->[F_RESIDUE]]->[$_[1]->[F_RESIDUE]] }
sub _POW { $pow[$_[0]->[F_RESIDUE]]->($_[1]) }
sub _INV { $_[0]->[F_RESIDUE]? $_[0]: Math::ModInt->undefined }
sub _NEW { $base[$_[1] % 3] }

sub _DIV {
    my $this = $_[0]->[F_RESIDUE];
    my $that = $_[1]->[F_RESIDUE];
    return $that? $mul[$this]->[$that]: Math::ModInt->undefined;
}

sub residue        {      $_[0]->[F_RESIDUE]  }
sub signed_residue { $sgn[$_[0]->[F_RESIDUE]] }
sub modulus        { 3 }

1;

__END__