title: How to find the number of times a specific day of the week occurs during a given time period
body: <p>I am trying to handle groups which meet either once a week, twice a month or once a month - on any day of the week.  I would like to calculate the number of occurrences any given configuration would generate for a given time frame.  </p>
  
  <p>For example, say a group meets every Friday, from Jan 1 to June 30, how many times would they meet?  Or, if a group meets on Tuesday every other week, from Jan 1 to June 30, how many times would they meet?  Etc.</p>
  
  <p>Is this possible in php?  I'm not seeing a solution in the <a href="http://www.php.net/manual/en/class.dateinterval.php" rel="nofollow">DateInterval manual</a>.</p>
  
  <p>Thank you for any help.  </p>