var activePage="American"

function AmericanCalc(){

	var str= new String;

	if (H1.value=="") { H1.focus(); return false;}

    if (W1.value=="") { W1.focus(); return false;}

	str=eval(W1.value) / Math.pow(eval(H1.value)/100,2);



		BMI1.innerHTML =  str.toFixed(2);

		

	

}

function BritishCalc(){

	var str= new String;

	if (H21.value=="") { H21.focus(); return false;}

	if (W2.value=="") { W2.focus(); return false;}

	

	w= eval(W2.value)*0.4535924;  // to be converted to kg

	h= eval(H21.value)* 0.3048 + eval(H22.value)*0.0254 ;

	

	str= w / Math.pow(h,2);

	BMI2.innerHTML =  str.toFixed(2);

}



function ChangePage(tab){

	activePage=tab;

	switch (activePage)

	{

	case "American":

		activePage="British";

		break;

	case "British":

		activePage="American";

		break;

	}

	document.getElementById(activePage).style.display="none";

	switch (activePage)

	{

	case "American":

		activePage="British";

		break;

	case "British":

		activePage="American";

		break;

	}

	document.getElementById(activePage).style.display="inline";

	

}