The idea is simple:

First, build a two dimensional array -

original array:
 a b c d e f g h i j k l m ...

2-d array:
 a b c d
 e f g h
 ...
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When you print your data:

 for $x (0..4) {
  for $y (0..4) {
   print $temp_array[$y][$x], "\t";
  }
  print "\n";
 }
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Translate this into perl and you get your simple program.