Explain this function (mt_rand, base_convert)
<p>Recently I found a function to generate a random string of numbers and letters, and It was really compact and concise and I liked it alot.  The problem Is I have no idea what it is doing, or how to modify it.</p>

<p>Please can someone just explain to me step by step what is going on here.  I have tried looking up the functions alone but they don't seem to explain the things like 0x19A100 etc.</p>

<p>I would like to modify it to produce the same random string but only around 4 or 5 lettes long.  I don't just want to take the first few letters though, I wan't the function to properly produce.  I am trying to learn!</p>

<p>Here is the code:</p>

<pre><code>function genRndStr() 
    {   return strtoupper(base_convert(mt_rand(0x19A100, 0x39AA3FF), 35, 36));  }
</code></pre>

<p>Any help greatly appreciated! Thank you.</p>
