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#!/usr/bin/perl
# Produces a bell curve using Gaussian random numbers.
# Uses a standard deviation of 10 and a mean of 0.5 so that the '0' bin
# contains the randoms from 0 to 1 and so on.
# Plots +/- 4 standard deviations.
# Usage: bell.pl [COUNT]
# COUNT defaults to 1 million
use strict;
use warnings;
$| = 1;
use Math::Random::MT::Auto qw(gaussian);
MAIN:
{
my $count = (@ARGV) ? $ARGV[0] : 1000000;
my %bell;
# Get random numbers and put them in bins
print("Generating $count Gaussian random numbers. Please wait...");
for (1 .. $count) {
my $x = gaussian(10, 0.5);
# Handle 'rounding' using int()
if ($x < 0) {
$x = int($x-1);
} else {
$x = int($x);
}
# Make sure the tails don't overflow
if ($x > 40) {
$x = 40;
} elsif ($x < -40) {
$x = -40;
}
$bell{$x}++;
}
# Find the max bin size for scaling the output
my $max = 0;
while (my $key = each(%bell)) {
if ($max < $bell{$key}) {
$max = $bell{$key};
}
}
# Output the graph
print("\n");
for my $key (sort { $a <=> $b } (keys(%bell))) {
my $len = int(79.0 * $bell{$key}/$max);
print(':', '*' x $len, "\n");
}
}
exit(0);
# EOF
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