if (document.getElementById)
{
	DOMtype = "std";
}
else if (document.all)
{
	DOMtype = "ie4";
}
else if (document.layers)
{
	DOMtype = "ns4";
}


// **************************************************************************
// grab object by ID on page
function grabobj(objname) // v1.0
{

var ret = null;
	switch (DOMtype)
	{
		case "std":
		{
			ret = document.getElementById(objname);
		}
		break;

		case "ie4":
		{
			ret = document.all[objname];
		}
		break;
		case "ns4":
		{
			ret = document.layers[objname];
		}
		break;
	}
return ret;
}

function isNumeric(sText)
{
   var ValidChars = "0123456789.";
   var IsNumber=true;
   var Char;
   for (i = 0; i < sText.length && IsNumber == true; i++) 
      { 
      Char = sText.charAt(i); 
      if (ValidChars.indexOf(Char) == -1) 
         {
         IsNumber = false;
         }
      }
   return IsNumber;
}
function roundNumber(num, dec) {
	var result = Math.round(num*Math.pow(10,dec))/Math.pow(10,dec);
	return result;
}
function calcBMI ()
{

var errors="";

if (!grabobj("bmi_height").value) errors+="Please enter a Height in metres\n";
if (!grabobj("bmi_kg").value) errors+="Please enter a Weight in kilograms\n";
if (!isNumeric(grabobj("bmi_height").value)) errors+="Height in metres should be a valid number\n";
if (!isNumeric(grabobj("bmi_kg").value)) errors+="Weight in kilograms should be a valid number\n";

 if (errors)
 {
	alert(errors);
 } else {
	var height=grabobj("bmi_height").value;
	var height2=roundNumber(height*height,2);
	grabobj("bmi_math1").innerHTML=height+"x"+height+"<br />=&nbsp;"+height2;
	var bmitotal=roundNumber(grabobj("bmi_kg").value/height2,2);
	grabobj("bmi_math2").innerHTML=grabobj("bmi_kg").value+"kg"+" / "+height2+"<br />=&nbsp;"+bmitotal;
	grabobj("bmi_result").innerHTML="<strong>"+bmitotal+"</strong>";
 }
}
function calcWHR ()
{
var errors="";

if (!grabobj("waist").value) errors+="Please enter your waist measurement in inches\n";
if (!grabobj("hip").value) errors+="Please enter your hip measurement in inches\n";
if (!isNumeric(grabobj("waist").value)) errors+="Waist measurement in inches should be a valid number\n";
if (!isNumeric(grabobj("hip").value)) errors+="Hip measurement in inches should be a valid number\n";

 if (errors)
 {
	alert(errors);
 } else {
	grabobj("whr_result").innerHTML="<strong>"+roundNumber(grabobj("waist").value/grabobj("hip").value,2)+"</strong>";
 }
}