1 files changed, 59 insertions, 0 deletions
diff --git a/challenge-159/perl/ch-2.pl b/challenge-159/perl/ch-2.pl
new file mode 100644
index 0000000000..8efb6f5c41
--- /dev/null
+++ b/challenge-159/perl/ch-2.pl
@@ -0,0 +1,59 @@
+#!/usr/bin/perl
+# The Weekly Challenge 159
+# Task 2 Moebius Function
+# Usage: ch-2.pl $N
+use v5.22.0;
+use warnings;
+use Math::Complex;
+use List::Util qw/any/;
+use POSIX;
+
+use constant PI => 2*acos(0);
+
+
+if (defined($ARGV[0])) {
+    my $N =  $ARGV[0];
+    say "mu($N) = ", mo($N);
+}
+
+
+sub irn {
+    my $i = $_[0];
+    my $n = $_[1];
+    return Math::Complex->make(
+        cos 2*PI*$i/$n, sin 2*PI*$i/$n
+    );
+}
+
+sub mo {
+    my $n = $_[0];
+    return 1 if $n == 1;
+    return -1 if $n == 2;
+    my $sum = irn(1, $n);
+    for my $i (2..$n-1) {
+        next if any { ($i*$_) % $n == 0} (2..$n-1);
+        $sum += irn($i, $n); 
+    }
+    # say "# intermediate sum: ", Re($sum), "\n\n";
+    return floor(Re($sum)+0.5);
+}
+
+use Test::More tests => 18;
+ok mo(2) == -1, "test for 2";
+ok mo(5) == -1, "Example 1";
+ok mo(10) == 1, "Example 2";
+ok mo(20) == 0, "Example 3";
+ok mo(22) == 1, "test for 22";
+ok mo(41) == -1, "test for 41";
+ok mo(42) == -1, "test for 42";
+ok mo(43) == -1, "test for 43";
+ok mo(44) == 0, "test for 44";
+ok mo(45) == 0, "test for 44";
+ok mo(46) == 1, "test for 46";
+ok mo(47) == -1, "test for 47";
+ok mo(48) == 0, "test for 48";
+ok mo(49) == 0, "test for 49";
+ok mo(50) == 0, "test for 50";
+ok mo(3276) == 0, "test for 3276";
+ok mo(3277) == 1, "test for 3277";
+ok mo(3278) == -1, "test for 3278";