//power 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 calculatepower (obj) {
	if ((obj.voltage_1.value=="") || (obj.voltage_1.value=="-") || (obj.current_1.value=="") || (obj.current_1.value=="-"))
		{SetText("power_1","?");}
	else{
		with (Math) {
			v=calculatemult2(obj.voltagemult_1.selectedIndex,abs(eval(obj.voltage_1.value)));
			a=calculatemult2(obj.currentmult_1.selectedIndex,abs(eval(obj.current_1.value)));
		}
		p = format(v * a);
		SetText("power_1", p + " Watts");
	}
}

function calculatevoltage (obj) {
	if ((obj.power_2.value=="") || (obj.power_2.value=="-") || (obj.current_2.value=="") || (obj.current_2.value=="-"))
		{SetText("voltage_2","?");}
	else{
		with (Math) {
			p=calculatemult2(obj.powermult_2.selectedIndex,abs(eval(obj.power_2.value)));
			a=calculatemult2(obj.currentmult_2.selectedIndex,abs(eval(obj.current_2.value)));
		}
		v = format(p / a);
		SetText("voltage_2", v + " Volts");
	}
}

function calculatecurrent (obj) {
	if ((obj.power_3.value=="") || (obj.power_3.value=="-") || (obj.voltage_3.value=="") || (obj.voltage_3.value=="-"))
		{SetText("current_3","?");}
	else{
		with (Math) {
			p=calculatemult2(obj.powermult_3.selectedIndex,abs(eval(obj.power_3.value)));
			v=calculatemult2(obj.voltagemult_3.selectedIndex,abs(eval(obj.voltage_3.value)));
		}
		a= format(p / v);
		SetText("current_3", a + " Amps");
	}
}

function calculaterespower (obj) {
	if ((obj.current_4.value=="") || (obj.current_4.value=="-") || (obj.resistance_4.value=="") || (obj.resistance_4.value=="-"))
		{SetText("power_4","?");}
	else{
		with (Math) {
			a=calculatemult2(obj.currentmult_4.selectedIndex,abs(eval(obj.current_4.value)));
			r=calculatemult1(obj.resistancemult_4.selectedIndex,abs(eval(obj.resistance_4.value)));
		}
		p= format(a * a * r);
		SetText("power_4", p + " Watts");
	}
}