Clarity on behaviour of mt_getrandmax() and mt_rand()'s max

git-svn-id: https://svn.php.net/repository/phpdoc/en/trunk@335710 c90b9560-bf6c-de11-be94-00142212c4b1

reference/math/functions/mt-getrandmax.xml

@@ -19,7 +19,10 @@
  <refsect1 role="returnvalues">
   &reftitle.returnvalues;
   <para>
-   Returns the maximum random value returned by <function>mt_rand</function>
+   Returns the maximum random value returned by a call to
+   <function>mt_rand</function> without arguments, which is the maximum value 
+   that can be used for its <function>max</function> parameter without the
+   result being scaled up (and therefore less random).
   </para>
  </refsect1>
  <refsect1 role="examples">

reference/math/functions/mt-rand.xml

@@ -124,6 +124,9 @@ echo mt_rand(5, 15);
     The distribution of <function>mt_rand</function> return values is biased
     towards even numbers on 64-bit builds of PHP when
     <parameter>max</parameter> is beyond <literal>2^32</literal>.
+    This is because if <parameter>max</parameter> is greater than 
+    the value returned by <function>mt_getrandmax</function>, the output of the
+    random number generator must be scaled up.
    </para>
   </caution>
  </refsect1>