var roomvalue=1;
var aspectvalue=1;
var winvalue=1.1;
var twentyPercentMore=1.2;
var degreesCDifferential=37;
var BTU2KWH=3.414;
var hmFiddle=0.75;
function precalccheck(form) {
	if (form.roomtype.value==""||form.aspect.value==""||form.length.value==""||form.width.value==""||form.height.value==""){
		alert("\nPlease enter a length, width, & height.");
		return false;
	}
	return true;
}
function calcbtu(form) {
	if (precalccheck(form)) {
		var basicHeatReq=(form.length.value*form.width.value*form.height.value)*roomvalue*winvalue*aspectvalue*37*5*.75;
        	form.btuavg.value=Math.round(basicHeatReq*1.2/25)*25;
        	form.btumin.value=Math.round(basicHeatReq/25)*25;
		form.wattsavg.value=Math.round(basicHeatReq*1.2/3.414/25)*25; 
		form.wattsmin.value=Math.round(basicHeatReq/3.414/25)*25;    
	}
	return;
}


////
// Calculate feet given meters and set the .value of input with id inputToSet
// i: meters		- number value to convert
// 	  inputToSet	- id of input whose value to set
// o: Sets INPUT, inputToSet, 
function btuSetFeetFromMeters(meters, inputToSet) {
	if (!(ele = document.getElementById(inputToSet)))
		return false;
		
	var feet = '';

	// only set the value to non-empty if meters isnt empty or zero
	if (parseFloat(meters) == meters)
		feet = meters * 100 / 2.54 / 12;
	
	if (meters == '')
		ele.value = '';
	else if (meters == 0)
		ele.value = 0;
	else
		ele.value = (Math.round(feet*100)/100).toString();	
}

////
// Calculate feet given meters and set the .value of input with id inputToSet
// i: meters		- number value to convert
// 	  inputToSet	- id of input whose value to set
// o: Sets INPUT, inputToSet, 
function btuSetMetersFromFeet(feet, inputToSet) {
	if (!(ele = document.getElementById(inputToSet)))
		return false;
		
	var meters = '';

	// only set the value to non-empty if meters isnt empty or zero
	if (parseFloat(feet) == feet)
		meters = feet * 12 * 2.54 / 100;
	
	if (feet == '')
		ele.value = '';
	else if (feet == 0)
		ele.value = 0;
	else
		ele.value = (Math.round(meters*100)/100).toString();	
}