Problem of Apollonius: Difference between revisions
Added Perl example
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print_circle r2;
;;</lang>
=={{header|Perl}}==
{{trans|Perl 6}}
<lang perl>use utf8;
package Circle;
sub new {
my ($class, $args) = @_;
my $self = {
x => $args->{x},
y => $args->{y},
r => $args->{r},
};
bless $self, $class;
}
sub show {
my ($self, $args) = @_;
sprintf "x =%7.3f y =%7.3f r =%7.3f\n", $args->{x}, $args->{y}, $args->{r};
}
package main;
sub circle {
my($x,$y,$r) = @_;
Circle->new({ x => $x, y=> $y, r => $r });
}
sub solve_Apollonius {
my($c1, $c2, $c3, $s1, $s2, $s3) = @_;
my $𝑣11 = 2 * $c2->{x} - 2 * $c1->{x};
my $𝑣12 = 2 * $c2->{y} - 2 * $c1->{y};
my $𝑣13 = $c1->{x}**2 - $c2->{x}**2 + $c1->{y}**2 - $c2->{y}**2 - $c1->{r}**2 + $c2->{r}**2;
my $𝑣14 = 2 * $s2 * $c2->{r} - 2 * $s1 * $c1->{r};
my $𝑣21 = 2 * $c3->{x} - 2 * $c2->{x};
my $𝑣22 = 2 * $c3->{y} - 2 * $c2->{y};
my $𝑣23 = $c2->{x}**2 - $c3->{x}**2 + $c2->{y}**2 - $c3->{y}**2 - $c2->{r}**2 + $c3->{r}**2;
my $𝑣24 = 2 * $s3 * $c3->{r} - 2 * $s2 * $c2->{r};
my $𝑤12 = $𝑣12 / $𝑣11;
my $𝑤13 = $𝑣13 / $𝑣11;
my $𝑤14 = $𝑣14 / $𝑣11;
my $𝑤22 = $𝑣22 / $𝑣21 - $𝑤12;
my $𝑤23 = $𝑣23 / $𝑣21 - $𝑤13;
my $𝑤24 = $𝑣24 / $𝑣21 - $𝑤14;
my $𝑃 = -$𝑤23 / $𝑤22;
my $𝑄 = $𝑤24 / $𝑤22;
my $𝑀 = -$𝑤12 * $𝑃 - $𝑤13;
my $𝑁 = $𝑤14 - $𝑤12 * $𝑄;
my $𝑎 = $𝑁**2 + $𝑄**2 - 1;
my $𝑏 = 2 * $𝑀 * $𝑁 - 2 * $𝑁 * $c1->{x} + 2 * $𝑃 * $𝑄 - 2 * $𝑄 * $c1->{y} + 2 * $s1 * $c1->{r};
my $𝑐 = $c1->{x}**2 + $𝑀**2 - 2 * $𝑀 * $c1->{x} + $𝑃**2 + $c1->{y}**2 - 2 * $𝑃 * $c1->{y} - $c1->{r}**2;
my $𝐷 = $𝑏**2 - 4 * $𝑎 * $𝑐;
my $rs = (-$𝑏 - sqrt $𝐷) / (2 * $𝑎);
my $xs = $𝑀 + $𝑁 * $rs;
my $ys = $𝑃 + $𝑄 * $rs;
circle($xs, $ys, $rs);
}
$c1 = circle(0, 0, 1);
$c2 = circle(4, 0, 1);
$c3 = circle(2, 4, 2);
print Circle->show( solve_Apollonius $c1, $c2, $c3, (-1,1)[qw<1 1 1>]);
print Circle->show( solve_Apollonius $c1, $c2, $c3, (-1,1)[qw<0 0 0>]);</lang>
{{out}}
<pre>x = 2.000 y = 2.100 r = 3.900
x = 2.000 y = 0.833 r = 1.167
</pre>
=={{header|Perl 6}}==
This program is written mostly in the "sigilless" style for several reasons. First, sigils tend to imply variables, and these sigilless symbols are not variables, but readonly bindings to values that are calculated only once, so leaving off the sigil emphasizes the fact that they are not variables, but merely named intermediate results.
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