var r34 = new Array(0, 0, 0, 0, 0, 0);
var r56 = new Array(0, 0, 0, 0, 0, 0, 0, 0);

function getval(num) {
	var idx = eval("document.resistors.r" + num + ".selectedIndex");
	if (idx <= 0) return "";
	var val = eval("document.resistors.r" + num + ".options[idx].value");
	return val;
}

function update(num1, num2) {
	num = num1 * 10 + num2;
	eval("r" + num1 + "[" + num2 + "] = getval(" + num + ")");
	update_result(num1);
}

function update_result(num) {
	if (num == 34) {
		if (("" + r34[1] != "") &&
			("" + r34[2] != "") &&
			("" + r34[3] != "")) {
			var resistance = (1 * r34[1] + 1 * r34[2]) * r34[3];
			var units = 'Ohms';
			if (resistance >= 1000000000) {
				resistance /= 1000000000;
				units = 'GOhms';
			} else if (resistance >= 1000000) {
				resistance /= 1000000;
				units = 'MOhms';
			} else if (resistance >= 1000) {
				resistance /= 1000;
				units = 'kOhms';
			}
			if (resistance != parseInt(resistance)) {
				resistance = parseInt(resistance * 100) / 100.0;
			}
			resistance += " " + units;

			document.resistors.resistance34.value = resistance;
		}
		if ("" + r34[4] != "") {
			tolerance = r34[4];

			document.resistors.tolerance34.value = tolerance;
		}
	} else if (num == 56) {
		if (("" + r56[1] != "") &&
			("" + r56[2] != "") &&
			("" + r56[3] != "") &&
			("" + r56[4] != "")) {
			var resistance = (1 * r56[1] + 1 * r56[2] + 1 * r56[3]) * r56[4];
			var units = 'Ohms';
			if (resistance >= 1000000000) {
				resistance /= 1000000000;
				units = 'GOhms';
			} else if (resistance >= 1000000) {
				resistance /= 1000000;
				units = 'MOhms';
			} else if (resistance >= 1000) {
				resistance /= 1000;
				units = 'kOhms';
			}
			if (resistance != parseInt(resistance)) {
				resistance = parseInt(resistance * 100) / 100.0;
			}
			resistance += " " + units;

			document.resistors.resistance56.value = resistance;
		}
		if ("" + r56[5] != "") {
			tolerance = r56[5];
			document.resistors.tolerance56.value = tolerance;
		}
		if ("" + r56[6] != "") {
			tempcoeff = r56[6];
			document.resistors.tempcoeff56.value = tempcoeff;
		}
	}
}