function median ($a)
{
  //variable and initializations
  $the_median = 0.0;
  $index_1 = 0;
  $index_2 = 0;

  //sort the array
  sort($a);

  //count the number of elements
  $number_of_elements = count($a);

  //determine if odd or even
  $odd = $number_of_elements % 2;

  //odd take the middle number
  if ($odd == 1)
  {
    //determine the middle
    $the_index_1 = $number_of_elements / 2;

    //cast to integer
    settype($the_index_1, "integer");

    //calculate the median
    $the_median = $a[$the_index_1];
  }
  else
  {
    //determine the two middle numbers
    $the_index_1 = $number_of_elements / 2;
    $the_index_2 = $the_index_1 - 1;

    //calculate the median
    $the_median = ($a[$the_index_1] + $a[$the_index_2]) / 2;
  }

  return $the_median;
}

<?
include ("ajstatistics.php");
$a = array(0, 1, 2, 3, 4, 5);

$the_median = median($a);

echo "a[0] = $a[0]<br>";
echo "a[1] = $a[1]<br>";
echo "a[2] = $a[2]<br>";
echo "a[3] = $a[3]<br>";
echo "a[4] = $a[4]<br>";
echo "a[5] = $a[5]<br>";
echo "the_median = $the_median<br>";
?>