// JavaScript Document
function calculateVertical(form)
// calculate the lengths in decimal feet of vertical
// call other functions (above) to calculate fractional feet/inches and meters
// display results in form fields //
	{
		var factor;
		var frequency;
		var radial_length;
		var element_length;
		var quarter_wave_factor = 234;
		factor=roundNumber(form.factor.value,2);
		frequency=roundNumber(form.frequency.value,2);
		element_length=roundNumber((factor/frequency),2);
		radial_length = roundNumber(quarter_wave_factor/frequency,2);
		if (element_length>0)
			{
				form.element_feet.value = String(roundNumber(element_length,2))+" ft";
				form.element_feet_inches.value = fractional_feet_inches(element_length);
				form.element_meters.value = String(meters_from_feet(element_length))+" meters";
				form.radial_feet.value = String(roundNumber(radial_length,2))+" ft";
				form.radial_feet_inches.value = fractional_feet_inches(radial_length);
				form.radial_meters.value = String(meters_from_feet(radial_length))+" meters";
			}
		else
			{
				clearResults(form);
			}
	}

function reportSelectedRadioButtonValue(form)
// cycle through the passed radio group and insert the selected value into the factor field on the form
	{
		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.factor.value=selected_value;
		calculateVertical(form);
	}
	
function clearResults(form)
	{
		form.element_feet.value = "";
		form.element_feet_inches.value = "";
		form.element_meters.value = "";
		form.radial_feet.value = "";
		form.radial_feet_inches.value = "";
		form.radial_meters.value = "";
	}
	
function checkEnter(form)
	{
		var characterCode
		if (window.event)
			{ 
				e = window.event;
				if (e.keyCode == 13)
					{
						calculateVertical(form);
					}
			}
	}