If you roll one die many times, you wind up with a uniform distribution of results. If you roll a pair of dice many times, you get a lot more results in the midrange than on the extremes. What if you want something in-between? A bell curve, but not quite so tall (that is, not quite so center-weighted)?

Obviously, you roll 1.5 dice. Or 1.2 dice. The sub below allows you to roll any positive number (*) of dice. I've included a little wrapper program so you can see the distribution of results of 50000 throws.

The parameters are, in order: lowest value to return (integer), number of distinct possible return values (integer), how many dice to use.

* numbers smaller than 1 all act like 1

my $range=12;
my $low_end=6;
my $dice=1.2;
my %freq = ();

for (1..50000) {
  $freq{ roll_dice($low_end, $range, $dice) }++
}
print "$_: $freq{$_}\n" for sort {$a<=>$b} keys %freq;

sub roll_dice {
  my ($low_end, $range, $dice) = @_;
  my $result = 0;
  my $i;
  for ($i = $dice; $i >=1; --$i) {
      $result += rand($range);
  }
  $result += rand($range) * $i;
  int($low_end) + int($result/$dice);
}

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In reply to Fractional dice by Roy Johnson

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