function calculateBMI(){

	var blnOK = true;

	var objForm	= document.getElementById("frmbmi");
		
	var objWeight		= objForm.weight;
	var objHeight		= objForm.height;
	var objMeasureType	= objForm.measuretype;
	
	var objBMIscore		= document.getElementById("bmiscore");

	var intWeight		= objWeight.value;
	var intHeight		= objHeight.value;
	var strMeasureType	= "";
	
	// Skriver fejlmeddelelse hvis enten h eller v ikke er et tal
	if(isNaN(intWeight)){
		alert("Weight must be a number !");
		objWeight.focus();
		blnOK = false;
	}
	
	if((isNaN(intHeight)) && (blnOK)){
		alert("Height must be a number !");
		objHeight.focus();
		blnOK = false;
	}	

	if(blnOK){
		for(var i=0; i < objMeasureType.length ; i++){
			if(objMeasureType[i].checked)
				strMeasureType = String(objMeasureType[i].value);
		}
		
		// Konverterer fod til meter, pund til kilogram.
		if(strMeasureType == "us"){
			intHeight = (intHeight * 0.3048);
			intWeight = (intWeight * 0.4536); 
		}

		// Laver et afrundet resultat
		var intBMI = (intWeight/(intHeight*intHeight));
		intBMI = (intBMI*10);
		intBMI = Math.round(intBMI);
		intBMI = (intBMI/10);
	
		// Udskriver resultatet
		objBMIscore.innerHTML = intBMI;
	}
}