Im using DatePicker plugin for a project. But I want to Disable dates older than today .(User couldnt select the old dates) My js is:

PHP Code:
datePickerController.createDatePicker({
formElements:{"inp1":"d-ds-m-ds-Y"} }); 
In manual :Both methods accept an Object that represents the dates or date ranges to disable. I couldnt disable the old days yet with many trial and error. Can you please show me any way to do this? Thanks in advance
PHP Code:
datePickerController.setRangeLow("myElementID",$today);
datePickerController.setRangeHigh("myElementID",$old_dayes); 
I want to set dynamic date in ("myElementID","20081201") . Date ranges : $today and $old_days = 'dates older than $today'