Refactor this jQuery datepicker code to be as small as possible
You'll want to use setDefaults to clean up your code a bit. Also with a few variables you can clean it up even more.

$.datepicker.setDefaults({
    showOn: 'both',
    buttonImage: '/assets/images/calendar_symbol.png',
    buttonImageOnly: true,
    dateFormat: 'dd/mm/yy',
    constrainInput: true
});

var minDate = new Date(
    &lt;?php echo date("Y")?&gt;, 
    &lt;?php echo date("m")-1?&gt;, 
    &lt;?php echo date("d")?&gt;
);

var setEndDate = function() {
    $('#enddate').val($('#startdate').val());
};

$('#startdate').datepicker({
    minDate: minDate ,
    onClose: setEndDate 
});

$('#enddate').datepicker({
    minDate: minDate 
});

$('#filter_startdate').datepicker({
    onClose: setEndDate 
});

$('#filter_enddate').datepicker();