PHP array/function problem

I'm having a problem trying to understand why a predefined array is not being echoed/print_r when requested from inside a function.

the array is global(?) by being defined outside the function(s). I can't seem to see why it wont show the array?

It works outside the function

$mondayset=array("setone", "settwo", "setthree", "setfour");

$tuesdayset=array(""setfive", "setsix", setseven");

function dosets ($pubdate)

          {

  $caledardate = explode("/", $pubdate);

  $timestamp = strtotime("$caledardate[2]"."-"."$caledardate[0]"."-"."$caledardate[1]");

  if(date('D', $timestamp) === 'Mon')

     {

          echo "It is Monday today\n";

          print_r($mondayset);

     }

$thedate = 12/2/2013

dosets($thedate)