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diff --git a/challenge-257/jo-37/perl/ch-2.pl b/challenge-257/jo-37/perl/ch-2.pl
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+++ b/challenge-257/jo-37/perl/ch-2.pl
@@ -0,0 +1,119 @@
+#!/usr/bin/perl -s
+
+use v5.24;
+use Test2::V0 '!float';
+use PDL;
+use PDL::NiceSlice;
+
+our ($tests, $examples);
+
+run_tests() if $tests || $examples;	# does not return
+
+die <<EOS unless @ARGV;
+usage: $0 [-examples] [-tests] [M]
+
+-examples
+    run the examples from the challenge
+ 
+-tests
+    run some tests
+
+M
+    a matrix in any form accepted by the PDL string constructor, e.g.
+    '[[0, 1,-2, 0, 1], [0, 0, 0, 1, 3], [0, 0, 0, 0, 0], [0, 0, 0, 0, 0]]'
+
+EOS
+
+
+### Input and Output
+
+say 0 + !!is_reduced_echelon("@ARGV");
+
+
+### Implementation
+
+sub is_reduced_echelon {
+	my $m = pdl @_;
+
+    my $allones = whichND($m == 1);
+    my $firstidx = which($allones->(1)->enumvec == 0);
+    my $firstones = $allones->dice('X', $firstidx);
+    return unless $firstones->dim(1) < 2 ||
+        all $firstones((0),0:-2) < $firstones((0),1:-1);
+    for my $firstone ($firstones->dog) {
+        my ($col, $row) = $firstone->list;
+        return unless 1 == sum $m->dice('X', $row)->(0:$col) != 0;
+        return unless 1 == sum $m->dice($col, 'X')->(,0:$row) != 0;
+    }
+    my $zeros = which $m->orover == 0;
+    return unless !$firstones->ngood || !$zeros->ngood ||
+        $firstones->((1))->max < $zeros->min;
+    
+    return unless $zeros->dim(0) + $firstidx->dim(0) == $m->dim(1);
+    
+    1;
+}
+
+
+### Examples and tests
+
+sub run_tests {
+    SKIP: {
+        skip "examples" unless $examples;
+
+        ok !is_reduced_echelon([
+                [1, 1, 0],
+                [0, 1, 0],
+                [0, 0, 0]
+            ]), 'example 1';
+
+        ok is_reduced_echelon([
+                [0, 1,-2, 0, 1],
+                [0, 0, 0, 1, 3],
+                [0, 0, 0, 0, 0],
+                [0, 0, 0, 0, 0]
+            ]), 'example 2';
+
+        ok is_reduced_echelon([
+                [1, 0, 0, 4],
+                [0, 1, 0, 7],
+                [0, 0, 1,-1]
+            ]), 'example 3';
+
+        ok !is_reduced_echelon([
+                  [0, 1,-2, 0, 1],
+                  [0, 0, 0, 0, 0],
+                  [0, 0, 0, 1, 3],
+                  [0, 0, 0, 0, 0]
+             ]), 'example 4';
+
+        ok !is_reduced_echelon([
+                [0, 1, 0],
+                [1, 0, 0],
+                [0, 0, 0]
+             ]), 'example 5';
+
+        ok !is_reduced_echelon([
+                [4, 0, 0, 0],
+                [0, 1, 0, 7],
+                [0, 0, 1,-1]
+             ]), 'example 6';
+    }
+
+    SKIP: {
+        skip "tests" unless $tests;
+
+        ok is_reduced_echelon([
+                [0, 0, 0],
+                [0, 0, 0]
+            ]), 'zero matrix';
+
+        ok is_reduced_echelon([
+                [0, 0, 1],
+                [0, 0, 0]
+            ]), 'single row';
+	}
+
+    done_testing;
+    exit;
+}