41 lines
1.3 KiB
Perl
41 lines
1.3 KiB
Perl
package EC;
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{
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our ($A, $B) = (0, 7);
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package EC::Point;
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sub new { my $class = shift; bless [ @_ ], $class }
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sub zero { bless [], shift }
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sub x { shift->[0] }; sub y { shift->[1] };
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sub double {
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my $self = shift;
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return $self unless @$self;
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my $L = (3 * $self->x**2) / (2*$self->y);
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my $x = $L**2 - 2*$self->x;
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bless [ $x, $L * ($self->x - $x) - $self->y ], ref $self;
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}
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use overload
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'==' => sub { my ($p, $q) = @_; $p->x == $q->x and $p->y == $q->y },
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'+' => sub {
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my ($p, $q) = @_;
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return $p->double if $p == $q;
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return $p unless @$q;
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return $q unless @$p;
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my $slope = ($q->y - $p->y) / ($q->x - $p->x);
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my $x = $slope**2 - $p->x - $q->x;
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bless [ $x, $slope * ($p->x - $x) - $p->y ], ref $p;
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},
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q{""} => sub {
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my $self = shift;
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return @$self
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? sprintf "EC-point at x=%f, y=%f", @$self
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: 'EC point at infinite';
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}
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}
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package Test;
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my $p = +EC::Point->new(-($EC::B - 1)**(1/3), 1);
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my $q = +EC::Point->new(-($EC::B - 4)**(1/3), 2);
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my $s = $p + $q, "\n";
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print "$_\n" for $p, $q, $s;
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print "check alignment... ";
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print abs(($q->x - $p->x)*(-$s->y - $p->y) - ($q->y - $p->y)*($s->x - $p->x)) < 0.001
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? "ok" : "wrong";
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