function getRadioButtonSelectedValue(ctrl)
{
    for(i=0;i<ctrl.length;i++)
    {
        if(ctrl[i].checked) 
        	{
        	return ctrl[i].value;
        	}
    }
}

function calcPrice(t) {
if(t=='k')
{
bbed = getRadioButtonSelectedValue(document.boekform.data_Babybed);
}

	//get relevant data from form fields
	vanD=parseInt(document.boekform.data_DatumvanD.value,10); // ,10 argument to parse as decimal number
	vanM=parseInt(document.boekform.data_DatumvanM.value,10) - 1; //month starts at 0 with JS Date
	vanJ=parseInt(document.boekform.data_DatumvanJ.value,10);
	tmD=parseInt(document.boekform.data_DatumtmD.value,10);
	tmM=parseInt(document.boekform.data_DatumtmM.value,10) - 1;	
	tmJ=parseInt(document.boekform.data_DatumtmJ.value,10);
	aantV=parseInt(document.boekform.data_Aantvolw.value,10);
	aantK=parseInt(document.boekform.data_AantkindG.value,10);
	extCharge=4.5; // price per day for persons > 2
	
	//review data
	if(isNaN(aantK)) {aantK=0}

	if ((vanJ < 2000) && (vanJ>0)) {
		vanJ = vanJ+2000;
		document.boekform.data_DatumvanJ.value=vanJ;
	}
	if ((tmJ < 2000) && (tmJ>0)) {
		tmJ = tmJ+2000
		document.boekform.data_DatumtmJ.value=tmJ;	
	
	}
	
	
	
	bbed = getRadioButtonSelectedValue(document.boekform.data_Babybed);
	if (bbed == 'J')
	{
		extBbed = 3;
	}
	else
	{
		extBbed = 0;
	}
	
	//create date variables and calculate number of days
	vanDatum = new Date(vanJ,vanM,vanD);
	tmDatum= new Date(tmJ,tmM,tmD);
	numDays=((tmDatum-vanDatum)/86400000); // 24*60*60*1000 (date calc gives milliseconds)
	numDays=numDays.toFixed(0); //some bug with date = 24-3-2006
	
	//determine price per day - based on # of days and discount
	if(discnt)
	{
		dayPrice=60;
		dayPriceFullWeek=54;
	}
	else
	{
		dayPrice=66;
		dayPriceFullWeek=60;
		dayPriceTwoWeeks=56;
	}
	
	
	
	//calculate price, number of people and total
	if (numDays>6) {dayPrice=dayPriceFullWeek} // discount if more than 6 days booked
	if (numDays>13) {dayPrice=dayPriceTwoWeeks} // discount if more than 13 days booked
	numPersons=aantV+aantK;
	if (numPersons>2) {
		aantExt=(numPersons-2);
	}else{
		aantExt=0;
	}
	total=(numDays*dayPrice)+(aantExt*extCharge*numDays)+(numDays*extBbed);
	
	total=total.toFixed(2);
	if (!isNaN(total) && (total>0)) {
		document.boekform.data_Price.value=total;
	}else{
		document.boekform.data_Price.value='';
	}
}