// JavaScript Document
function calculateDipole(form)
// calculate the lengths in decimal feet of dipole and inverted dipole
// call other functions (above) to calculate fractional feet/inches and meters
// display results in form fields //
	{
		var frequency = 0;
		var element_length = 0;
		var v_element_length = 0;
		var v_percent = 0;
		frequency = form.frequency.value;
		if (frequency > 0)
			{
				element_length = roundNumber((form.factor.value / frequency),2);
			}
		v_percent = form.vreductionpercent.value;
		if (v_percent > 0)
			{
				v_percent = roundNumber((1 - (v_percent / 100)),2);
				if (v_percent < 0)
					{
						v_percent = 0;
					}
				if (v_percent > 1)
					{
						v_percent = 0;
					}
				if (v_percent > 0)
					{
						v_element_length = roundNumber((element_length * v_percent),2);
					}
			}
		if (element_length > 0)
			{
				form.full_dipole.value = String(roundNumber(element_length,2))+" ft";
				form.full_dipole_feetinches.value = fractional_feet_inches(element_length);
				form.full_dipole_meters.value = String(meters_from_feet(element_length))+" meters";
				form.half_dipole.value = String(roundNumber((element_length/2),2))+" ft";
				form.half_dipole_feetinches.value = fractional_feet_inches(element_length/2);
				form.half_dipole_meters.value = String(meters_from_feet((element_length/2)))+" meters";
				if (v_element_length > 0)
					{
						form.full_v.value = String(roundNumber(v_element_length,2))+" ft";
						form.full_v_feetinches.value = fractional_feet_inches(v_element_length);
						form.full_v_meters.value = String(meters_from_feet(v_element_length))+" meters";
						form.half_v.value = String(roundNumber((v_element_length/2),2))+" ft";
						form.half_v_feetinches.value = fractional_feet_inches(v_element_length/2);
						form.half_v_meters.value = String(meters_from_feet((v_element_length/2)))+" meters";
					}
			}
		else
			{
				clearResults(form);
			}
	}
	
function reportSelectedRadioButtonValue(form)
// cycle through the passed radio group and insert the selected value into the inverted V reduction percent field on the form below
	{
		var selected_value="";
		var len=form.radio1.length;
		for (i=0; i<len; i++)
			{
				if (form.radio1[i].checked)
					{ 
						selected_value = form.radio1[i].value;
					}
				if (!selected_value=="")
					{
						break
					}
			}
		form.vreductionpercent.value = selected_value;
		clearResults(form);
		calculateDipole(form);
	}

function clearResults(form)
	{
		form.full_dipole.value = "";
		form.full_dipole_feetinches.value = "";
		form.full_dipole_meters.value = "";
		form.half_dipole.value = "";
		form.half_dipole_feetinches.value = "";
		form.half_dipole_meters.value = "";
		form.full_v.value = "";
		form.full_v_feetinches.value = "";
		form.full_v_meters.value = "";
		form.half_v.value = "";
		form.half_v_feetinches.value = "";
		form.half_v_meters.value = "";
	}
	
function checkEnter(form)
	{
		var characterCode
		if (window.event)
			{ 
				e = window.event;
				if (e.keyCode == 13)
					{
						calculateDipole(form);
					}
			}
	}