add solution week 26 task 2

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+#!/usr/bin/env perl
+# Author: Steven Wilson
+# Date: 2019-09-16
+# Week: 026
+
+# Task #2
+# Create a script that prints mean angles of the given list of angles in
+# degrees. Please read wiki page that explains the formula in details
+# with an example.
+# https://en.wikipedia.org/wiki/Mean_of_circular_quantities
+# usage: perl ch-2.pl 355 5 15
+# output: Mean of the angles 355 5 15 is 5
+
+use strict;
+use warnings;
+use feature qw/ say /;
+use Test::More;
+use List::Util qw/ sum /;
+use Math::Trig;
+
+my @t_angles = qw/ 355 5 15 /;
+
+ok( sprintf( "%.0f", calculate_circular_mean( \@t_angles ) ) == 5, "test circular mean" );
+ok( sprintf( "%.3f", mean_sines( \@t_angles ) ) == 0.086, "test mean sines" );
+ok( sprintf( "%.3f", mean_cosines( \@t_angles ) ) == 0.986, "test mean cosines" );
+done_testing();
+
+my @angles = @ARGV;
+
+say "Mean of the angles ",
+    join( " ", @angles, "is", calculate_circular_mean( \@angles ) );
+
+sub calculate_circular_mean {
+    my $ref_angles = shift;
+    my @angles     = @{$ref_angles};
+    my $s          = mean_sines($ref_angles);
+    my $c          = mean_cosines($ref_angles);
+    my $mean;
+    if ( $s > 0 && $c > 0 ) {
+        $mean = rad2deg( atan( $s / $c ) );
+    }
+    elsif ( $c < 0 ) {
+        $mean = rad2deg( atan( $s / $c ) ) + 180;
+    }
+    else {
+        $mean = rad2deg( atan( $s / $c ) ) + 360;
+    }
+    return $mean;
+}
+
+sub mean_cosines {
+    my $ref_angles  = shift;
+    my @angles      = @{$ref_angles};
+    my @cosines     = map { cos( deg2rad($_) ) } @angles;
+    my $sum_cosines = sum @cosines;
+    return ( $sum_cosines / @angles );
+
+}
+
+sub mean_sines {
+    my $ref_angles = shift;
+    my @angles     = @{$ref_angles};
+    my @sines      = map { sin( deg2rad($_) ) } @angles;
+    my $sum_sines  = sum @sines;
+    return ( $sum_sines / @angles );
+}