//ohms law calculator functions
//copyright Simon Carter 2001-2008
//Please contact me via www.electronics2000.co.uk if you wish to use these
//and ensure this header block remains intact

function computevolts (obj) {
	if ((obj.current_1.value=="") || (obj.current_1.value=="-") || (obj.resistance_1.value=="") || (obj.resistance_1.value=="-"))
		{SetText("voltage_1","?");}
	else{
		with (Math) {
		a1=abs(eval(obj.current_1.value));
		r1=abs(eval(obj.resistance_1.value));
		a1=calculatemult2(obj.currentmult_1.selectedIndex,a1);
		r1=calculatemult1(obj.resistancemult_1.selectedIndex,r1);
		}
	v1 = format(a1 * r1);
	SetText("voltage_1",v1 + " Volts");}
}

function computeamps (obj) {
	if ((obj.voltage_2.value=="") || (obj.voltage_2.value=="-") || (obj.resistance_2.value=="") || (obj.resistance_2.value=="-"))
		{SetText("current_2","?");}
	else{
		with (Math) {
		v2=eval(obj.voltage_2.value);
		r2=abs(eval(obj.resistance_2.value));
		v2=calculatemult2(obj.voltagemult_2.selectedIndex,v2);
		r2=calculatemult1(obj.resistancemult_2.selectedIndex,r2);
		}
	a2 = format(v2 / r2);
	SetText("current_2", a2 + " Amps");}
}

function computeohms (obj) {
	if ((obj.voltage_3.value=="") || (obj.voltage_3.value=="-") || (obj.current_3.value=="") || (obj.current_3.value=="-"))
		{SetText("resistance_3","?");
		SetText("prefresistance_3","?");}
	else{
		with (Math) {
			v3=abs(eval(obj.voltage_3.value));
			a3=abs(eval(obj.current_3.value));
			v3=calculatemult2(obj.voltagemult_3.selectedIndex,v3);
			a3=calculatemult2(obj.currentmult_3.selectedIndex,a3);
		}
		r3= v3 / a3;
		prefres3 = format((GetPrefRes(r3, getCheckedValue(obj.prefseries))));
		r3=format(r3);
		SetText("resistance_3",r3 + " Ohms");
		SetText("prefresistance_3", prefres3 + " Ohms");
	}
}