Description:
------------
Example output from the following script that generates 16 random numbers in the 
range from -1073741823 to 2147483647. It shows that the number 1073741825 was 
repeated 4 times, or 25% of the time. This output is typical and the repeated 
number is always 1073741825. The problem is less the smaller the magnitude of 
$min.


Test script:
---------------
<?php

printf("PHP_VERSION=%s\n",PHP_VERSION);
$min = -(mt_getrandmax()>>1);
$max = mt_getrandmax();
$count = isset($argv[1])?(int)$argv[1]:16;
printf("min=%d, max=%d, count=%d\n",$min,$max,$count);

$repeat_counts = array();

for ($i=0;$i<$count;$i++) {
  $random = mt_rand($min,$max);
  if (!isset($repeat_counts[$random])) {
    $repeat_counts[$random] = 0;
  }
  $repeat_counts[$random]++;
  //printf("%12d%s\n", abs($random),($random<0)?"-":"");
}

$max_repeat_count = max($repeat_counts);
$same_value_max = array();
if ($max_repeat_count > 1) {
  foreach ($repeat_counts as $value => $repeat_count) {
    if ($repeat_count >= $max_repeat_count) {
      $same_value_max[] = $value;
    }
  }
  printf("The following number/s was/were repeated %d times (%s%%): %s\n"
    ,$max_repeat_count
    ,number_format(($max_repeat_count/$count)*100.0,1)
    ,implode(", ",$same_value_max)
    );
}


Expected result:
----------------
PHP_VERSION=5.3.8
min=-1073741823, max=2147483647, count=16



Actual result:
--------------
PHP_VERSION=5.3.8
min=-1073741823, max=2147483647, count=16
The following number/s was/were repeated 4 times (25.0%): 1073741825