var inToM = new Array(1, 0.0254, 0.0254);
var lbToKg = new Array(1, 0.4536, 0.4536);
var sys = 0;
function calc() {
	document.getElementById("bmiNum").firstChild.nodeValue=" ";
	document.getElementById("enter").style.display='block';
	document.getElementById("bmiDiv").style.display='none';
	document.getElementById("under").style.display='none';
	document.getElementById("norm").style.display='none';
	document.getElementById("over").style.display='none';
	document.getElementById("obese").style.display='none';
	document.getElementById("sobese").style.display='none';
	var wt0 = 'wt'+sys+'0';
	var wt1 = 'wt'+sys+'1';
	var ht0 = 'ht'+sys+'0';
	var ht1 = 'ht'+sys+'1';
	var kgs = (document.getElementById(wt1).value*14+document.getElementById(wt0).value*1)*lbToKg[sys];
	var mts = (document.getElementById(ht1).value*12+document.getElementById(ht0).value*1)*inToM[sys];
	if (kgs>0 && kgs<500 && mts>0 && mts<5 ) {
		var bmi = Math.round(kgs*10/mts/mts)/10;
		var lvl = "";
		var group = "";
		if (bmi<18.5) {
			lvl = "under";
			group = "underweight"; 
		} else if (bmi<=25) {
			lvl = "norm";
			group = "healthy weight"; 
		} else if (bmi<=30) {
			lvl = "over";
			group = "overweight"; 
		} else if (bmi<=40) {
			lvl = "obese";
			group = "obese"; 
		} else {
			lvl = "sobese";
			group = "severely obese";
		}
		document.getElementById("enter").style.display='none';
		document.getElementById("bmiNum").firstChild.nodeValue = "Your BMI is "+bmi+" - "+group;
		document.getElementById("bmiDiv").style.display='block';
		document.getElementById(lvl).style.display='block';
	}
}
function changeSys(on, off1, off2) {
	sys = on;
	var onId = "s"+on;
	var offId1 = "s"+off1;
	var offId2 = "s"+off2;
	var bon = "b"+on;
	var boff1 = "b"+off1;
	var boff2 = "b"+off2;
	document.getElementById(onId).className='sysOn';
	document.getElementById(offId1).className='sysOff';
	document.getElementById(offId2).className='sysOff';
	document.getElementById(bon).className='silverBack';
	document.getElementById(boff1).className='whiteBack';
	document.getElementById(boff2).className='whiteBack';
	document.getElementById(on).style.display='block';
	document.getElementById(off1).style.display='none';
	document.getElementById(off2).style.display='none';
}