function oxygenCalc(form) {
	var pao2 = form.pao2.value;
	var map = form.map.value;
	var fio2 = form.fio2.value;

	if (!checkNum(fio2)) {
		alert("WARNING: Please enter the FiO2");
		form.fio2.select();
		form.fio2.focus();
		return false
	}

	if (!checkNum(map)) {
		alert("WARNING: Please enter the Mean Airway Pressure");
		form.map.select();
		form.map.focus();
		return false
	}

	if (!checkNum(pao2)) {
		alert("WARNING: Please enter the PaO2");
		form.pao2.select();
		form.pao2.focus();
		return false
	}

	if (fio2 > 1) {fio2 = fio2 / 100};
	
	var oi = fio2 * map * 100 / pao2;
	oi = rounding(oi,1);
	form.oi.value = oi;
	
	return true
}

function checkNum(val) {
        if ((val == null) || (isNaN(val)) || (val == "") || (val < 0)) {
                return false
        }
        return true;
}

function rounding(number,decimal) {
        multiplier = Math.pow(10,decimal);
        number = Math.round(number * multiplier) / multiplier;
        return number
}