window.onload = setDefaults;

function setDefaults() {
	var course = 3020;
	var flowrate = 12;
	var fuelPrice = 2870;
	var gazPrice = 1500;
	var economy = Math.round( ( fuelPrice - gazPrice * 1.1 ) * flowrate * 10);
	var installPrice = 630 * course;
	var runPayback = Math.round(installPrice * 1000 / economy);

	f1 = document.calculation;


        f1.flowrate.value = flowrate;
        f1.fuelPrice.value = fuelPrice;
        f1.gazPrice.value = gazPrice;
        f1.economy.value = economy;
        f1.installPrice.value = installPrice;
        f1.runPayback.value = runPayback;

	update();
}

function update() {
	f1 = document.calculation;

        flowrate = f1.flowrate.value;
        fuelPrice = f1.fuelPrice.value;
        gazPrice = f1.gazPrice.value;

        economy = Math.round( ( fuelPrice - gazPrice * 1.1 ) * flowrate * 10);

	installPrice = Math.round(f1.installPrice.value);

        runPayback = Math.round(installPrice * 1000 / economy);

        f1.flowrate.value = flowrate;
        f1.fuelPrice.value = fuelPrice;
        f1.gazPrice.value = gazPrice;
        f1.economy.value = economy;
        f1.installPrice.value = installPrice;
        f1.runPayback.value = runPayback;
}

function addNode(variable, value) {
	tmp = document.getElementById(variable);
//	txtNode=document.createTextNode(value);
	tmp.Value = 12;
}