The Snowcrash Test

Random Number Generation and Testing

This particular version of the test shows how choosing successive values of a seed cause the random number generator to make somewhat similar sequences.

A Picture from the Test

The Code for this Test


  Program to show how random number generator is influenced by its seed
  by Tom Anderson
  Copyright 2001 all rights reserved.
  Permission to distribute available from

  use strict;
  use PDL;
  use PDL::Graphics::PGPLOT;

  my $win = PDL::Graphics::PGPLOT::Window->new({Device => '/XSERVE/index.html'});
  my ($num_seeds, $num_rand_calls)= (150,150);
  $win->env( 0, $num_rand_calls, 0, $num_seeds );

  my @ra;
  for (my $s=0; $s<$num_seeds; $s++)
    srand $s;
    for (my $x=0; $x<$num_rand_calls; $x++)
      $ra[$s][$x]= rand;

  my $im= new PDL @ra;
  $win->label_axes('Number of calls to random number generator after seeding', 
                   'Seed', 'Random Numbers Displayed as Greyscale');


By toma