function catcalc(cal) {
                                var date = cal.date;
                                var time = date.getTime()
                                var fieldto = document.getElementById("toa");
                                var todate = new Date(fieldto.value);
                                
                                var fieldfrom = document.getElementById("froma");
                                var fromdate = new Date(fieldfrom.value);
                                if(fromdate > todate){
                                    var date2 = fromdate;
                                    fieldto.value = date2.print("%Y/%m/%d");
                                }
                            }
                            Calendar.setup({
                                inputField      :    "froma",   // id of the input field
                                ifFormat        :    "%Y/%m/%d",       // format of the input field
                                showsTime       :    false,
                                onUpdate        :    catcalc
                            });
                            Calendar.setup({
                                inputField     :    "toa",
                                ifFormat       :    "%Y/%m/%d",
                                showsTime      :    false,
                                onUpdate       :    catcalc
                            });