function stripBlanks(fld) {
	var result = "";
	var c = 0;
	for (i=0; i < fld.length; i++) {
		if (fld.charAt(i) != " " || c > 0) {
			result += fld.charAt(i);
			if (fld.charAt(i) != " ") c = result.length;
		}
	}
	return result.substr(0,c);
}

function calc(thisform) {
	var h = (parseInt(thisform.ft.value) * 12) + parseInt(thisform.inches.value);
	var w = stripBlanks(thisform.w.value);
	if (w == '') {
		alert("You must enter your weight");
		thisform.w.focus();
		return false;
	}
	if (w != Number(w) || (w == Number(w) < 25 || w > 1000)) {
		alert("Invalid weight entered");
		thisform.w.focus();
		return false;
	}
	w = parseFloat(w);
	thisform.f.value = Math.round(w/(h*h)*703);
}