function calculate() {
month = document.form.month.selectedIndex;
month = document.form.month.options[month].value;
day = document.form.day.selectedIndex;
day = document.form.day.options[day].value;
year = document.form.year.value;

var oyear=year

var dob = " "+ year +", "+month + ",  "+day;
var thenx = new Date(dob);

var year=thenx.getYear();
if (year<100) year="19" + thenx.getYear();
else year=thenx.getYear();

if (year > 1969) wyear=year;
else {
if (oyear<1900) {
if (oyear>1800) {
wrelyear= (eval(oyear)-1801)%(28);
wyear = wrelyear+1981;
}
else wyear = 1970 
}
else
if (oyear>1900) {wrelyear= (eval(oyear)-1901)%(28); 
wyear= wrelyear+1985
}
else 
if (oyear==1900) {wyear= 1990;
   }              
}
var dob = " "+ wyear +", "+month + ",  "+day;
var thenx = new Date(dob);

var theday = thenx.getDay()+1;
var date=thenx.getDate();

var weekday = new Array(6);
weekday[1]="Domingo";
weekday[2]="Lunes";
weekday[3]="Martes";
weekday[4]="Miércoles";
weekday[5]="Jueves";
weekday[6]="Viernes";
weekday[7]="Sábado";
if (day != date) {
alert("Sorry!  That appears to be an invalid date!"+day+" ..."+date+"::"+oyear+"..."+year+" "+dob+"=="+wyear+".-.-"+thenx+" "+day+" "+month);
dob="error";
}
else {
dayborn = weekday[theday];
dob = dayborn;
//alert("Tu naciste un " + dob);
   }
   var url="ConocerMas1/DiaRespuesta.asp?dob="+dob;
	var winName="";
	var features="width=400, height=410, scrollbars=yes";
	window.open(url,winName,features);
}