Challenge 026 task 2

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diff --git a/challenge-026/jo-37/perl/ch-2.pl b/challenge-026/jo-37/perl/ch-2.pl
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+++ b/challenge-026/jo-37/perl/ch-2.pl
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+#!/usr/bin/perl -s
+
+use v5.16;
+use Test2::V0 '!float';
+use warnings;
+use PDL;
+
+our ($tests, $examples);
+
+run_tests() if $tests || $examples;	# does not return
+
+die <<EOS unless @ARGV;
+usage: $0 [-examples] [-tests] [--] [D...]
+
+-examples
+    run the examples from the challenge
+ 
+-tests
+    run some tests
+
+D...
+    angles (in degrees)
+
+EOS
+
+
+### Input and Output
+
+say angle_mean(@ARGV);
+
+
+### Implementation
+
+use constant DEG2RAD => atan2(1,1) / 45;
+
+sub angle_mean {
+	my $r = DEG2RAD * pdl @_;
+    atan2($r->sin->average, $r->cos->average) / DEG2RAD;
+}
+
+
+### Examples and tests
+
+sub run_tests {
+    SKIP: {
+        skip "examples" unless $examples;
+
+        is angle_mean(355, 5, 15), 5, 'example from Wiki';
+    }
+
+    SKIP: {
+        skip "tests" unless $tests;
+	}
+
+    done_testing;
+    exit;
+}