function FahrenheitToCelsius(from, to) {
	var a = Math.round(((parseFloat(from)-32.0)/1.8)*100)/100;	
	myform.namedItem(to).value = (isNaN(a)?'':a);
}
function CelsiusToFahrenheit(from, to) {
	var a = Math.round((parseFloat(from)*1.8+32)*100)/100;
	myform.namedItem(to).value = (isNaN(a)?'':a);
}

function InchesToCentimeters(from, to) {
	var a = Math.round((parseFloat(from)*2.54)*100)/100;
	myform.namedItem(to).value = (isNaN(a)?'':a);
}
function CentimetersToInches(from, to) {
	var a = Math.round((parseFloat(from)*0.3937)*100)/100;
	myform.namedItem(to).value = (isNaN(a)?'':a);
}

function GallonsUSTOLiters(from, to) {
	var a = Math.round((parseFloat(from)* 3.7854118)*100)/100;
	myform.namedItem(to).value = (isNaN(a)?'':a);
}

function GallonsUSTOGallonsUK(from, to) {
	var a = Math.round((parseFloat(from)*0.8326742)*100)/100;
	myform.namedItem(to).value = (isNaN(a)?'':a);
}

function LitersTOGallonsUS(from, to) {
	var a = Math.round((parseFloat(from)* 0.2641721)*100)/100;
	myform.namedItem(to).value = (isNaN(a)?'':a);
}

function LitersTOGallonsUK(from, to) {
	var a = Math.round((parseFloat(from)*0.2199692)*100)/100;
	myform.namedItem(to).value = (isNaN(a)?'':a);
}

function GallonsUKTOLiters(from, to) {
	var a = Math.round((parseFloat(from)* 4.54609)*100)/100;
	myform.namedItem(to).value = (isNaN(a)?'':a);
}

function GallonsUKTOGallonsUS(from, to) {
	var a = Math.round((parseFloat(from)* 1.2009499)*100)/100;
	myform.namedItem(to).value = (isNaN(a)?'':a);
}


function GPHtoLPH(from, to) {
	var a = Math.round((parseFloat(from)* 3.7854118)*100)/100;
	myform.namedItem(to).value = (isNaN(a)?'':a);
}
function LPHtoGPH(from, to) {
	var a = Math.round((parseFloat(from)* 0.2641721)*100)/100;
	myform.namedItem(to).value = (isNaN(a)?'':a);
}

function dHToppm(from, to) {
	var a = Math.round((parseFloat(from)* 17.9)*100)/100;
	myform.namedItem(to).value = (isNaN(a)?'':a);
}
function ppmTodH(from, to) {
	var a = Math.round((parseFloat(from)/17.9)*100)/100;
	myform.namedItem(to).value = (isNaN(a)?'':a);
}

function calpsnc(l, w, d, p, res) {
	var ll = myform.namedItem(l).value;
	var ww = myform.namedItem(w).value;
	var dd = myform.namedItem(d).value;
	var pp = myform.namedItem(p).value;
	
	if(!isNaN(ll)&&!isNaN(ww)&&!isNaN(dd)&&!isNaN(pp))
		myform.namedItem(res).value = Math.round((ll*ww*dd*pp*0.00057871));
	else
		myform.namedItem(res).value = '' ;
}

function calc_tank_r(radio, l, w, h, gus, litrs) {

	var r_inp = document.getElementsByName(radio);
	var type=0;
	for(var i=0;i<r_inp.length;i++) {
		if(r_inp.item(i).checked) {
			if(r_inp.item(i).value == 'inches')
				type=1;
			else
				type=0;
			break;
		}
	}
	
	var ll = myform.namedItem(l).value;
	var ww = myform.namedItem(w).value;
	var hh = myform.namedItem(h).value;

	if(!isNaN(ll)&&!isNaN(ww)&&!isNaN(hh)) {
		if(type==1) {//inches 
			//calculate Gallons US
			myform.namedItem(gus).value = Math.round((ll*ww*hh*0.004329)*100)/100;
			//convert to Liters
			GallonsUSTOLiters(myform.namedItem(gus).value, litrs);
		}
		else {//centimetrs
			//calculate Liters
			 myform.namedItem(litrs).value = Math.round((ll*ww*hh*0.001)*100)/100;
			 //convert to Gallons US
			 LitersTOGallonsUS(myform.namedItem(litrs).value, gus);
		}
	}
	else {
		myform.namedItem(gus).value = '';
		myform.namedItem(litrs).value = '';
	}
}

function calc_tank_c(radio, r, h,  gus, litrs) {
	var r_inp = document.getElementsByName(radio);
	var type=0;
	for(var i=0;i<r_inp.length;i++) {
		if(r_inp.item(i).checked) {
			if(r_inp.item(i).value == 'inches')
				type=1;
			else
				type=0;
			break;
		}
	}

	var rr = myform.namedItem(r).value;
	var hh = myform.namedItem(h).value;
	
	if(!isNaN(rr)&&!isNaN(hh)) {
		if(type==1) {//inches 
			//calculate Gallons US
			myform.namedItem(gus).value = Math.round((3.142*rr*rr*hh*0.004329)*100)/100;
			//convert to Liters
			GallonsUSTOLiters(myform.namedItem(gus).value, litrs);
		}
		else {//centimetrs
			//calculate Liters
			 myform.namedItem(litrs).value = Math.round((3.142*rr*rr*hh*0.001)*100)/100;
			 //convert to Gallons US
			 LitersTOGallonsUS(myform.namedItem(litrs).value, gus);
		}
	}
	else {
		myform.namedItem(gus).value = '';
		myform.namedItem(litrs).value = '';
	}
}

function calc_tank_h(radio, w, h, gus, litrs) {
	var r_inp = document.getElementsByName(radio);
	var type=0;
	for(var i=0;i<r_inp.length;i++) {
		if(r_inp.item(i).checked) {
			if(r_inp.item(i).value == 'inches')
				type=1;
			else
				type=0;
			break;
		}
	}
	
	var ww = myform.namedItem(w).value;
	var hh = myform.namedItem(h).value;

	if(!isNaN(ww)&&!isNaN(hh)) {
		if(type==1) {//inches 
			//calculate Gallons US
			myform.namedItem(gus).value = Math.round((ww*ww*2.598*hh*0.004329)*100)/100;
			//convert to Liters
			GallonsUSTOLiters(myform.namedItem(gus).value, litrs);
		}
		else {//centimetrs
			//calculate Liters
			 myform.namedItem(litrs).value = Math.round((ww*ww*2.598*hh*0.001)*100)/100;
			 //convert to Gallons US
			 LitersTOGallonsUS(myform.namedItem(litrs).value, gus);
		}
	}
	else {
		myform.namedItem(gus).value = '';
		myform.namedItem(litrs).value = '';
	}
}

function update_span(id_v, v) {
	var a = document.getElementById(id_v);
	a.innerHTML = v;
}

function calc_row(indx) {
	var kwhr = myform.namedItem('cost_kwhr').value;
	var tw = parseFloat(myform.namedItem('tw_'+indx).value);
	var hpd = parseFloat(myform.namedItem('hpd_'+indx).value);
	
	if(!isNaN(tw) && !isNaN(hpd)) {
		myform.namedItem('cpm_'+indx).value = Math.round(((tw*hpd*kwhr*30)/1000)*100)/100;
		myform.namedItem('cpy_'+indx).value = Math.round((parseFloat(myform.namedItem('cpm_'+indx).value) * 12)*100)/100;
	}
	else {
		myform.namedItem('cpm_'+indx).value = 0;
		myform.namedItem('cpy_'+indx).value = 0;
	}

}

function calc_total() {
	var total_wats = 0.0;
	var av_pm = 0.0;
	var total_py = 0.0;
	
	var t,j=0;
	
	for(var i=1; i<10; i++) {
		t = parseFloat(myform.namedItem('tw_'+i).value)
		total_wats += (isNaN(t)?0.0:t);
		t = parseFloat(myform.namedItem('cpm_'+i).value);
		if(!isNaN(t) && t > 0) {
			av_pm += t;
			j++;
		}
		t = parseFloat(myform.namedItem('cpy_'+i).value);
		total_py += (isNaN(t)?0.0:t);
	}
	if(j>0)
		av_pm = av_pm/j;
	
	myform.namedItem('tw_total').value = Math.round(total_wats*100)/100;
	myform.namedItem('cpm_av').value = Math.round(av_pm*100)/100;
	myform.namedItem('cpy_total').value = Math.round(total_py*100)/100;
}

function update_kwhr() {
	for(var i=1; i<10; i++) {
		calc_row(i);
	}
}