function calculateSemiAnnuallyAPR()
{
    var FinanceCharge = (2 * document.getElementById("SAmt").value) - document.getElementById("AAmt").value;
    var denominator = document.getElementById("AAmt").value - document.getElementById("SAmt").value;
    var APR = (2 * FinanceCharge) / denominator;
    document.getElementById("SAPR").value = Math.round((APR * 100) * 100)/100;
}

function calculateQuarterlyAPR()
{
    var FinanceCharge = (4 * document.getElementById("QAmt").value) - document.getElementById("AAmt").value;
    var denominator = (5 * document.getElementById("AAmt").value) - (2 * document.getElementById("QAmt").value);
    var APR = (12 * FinanceCharge) / denominator;
    document.getElementById("QAPR").value = Math.round((APR * 100) * 100)/100;
}

function calculateMonthlyAPR()
{
    var FinanceCharge = (12 * document.getElementById("MAmt").value) - document.getElementById("AAmt").value;
    var denominator = (13 * document.getElementById("AAmt").value) + (42 * document.getElementById("MAmt").value);
    var APR = (36 * FinanceCharge) / denominator;
    document.getElementById("MAPR").value = Math.round((APR * 100) * 100)/100;
}

function calculateAPR()
{
    if (allInputFieldsEntered())
    {
	if ((document.getElementById("SAmt").value != "") && (parseFloat(document.getElementById("SAmt").value) != 0))
		calculateSemiAnnuallyAPR();
	if ((document.getElementById("QAmt").value != "") && (parseFloat(document.getElementById("QAmt").value) != 0))
		calculateQuarterlyAPR();
	if ((document.getElementById("MAmt").value > "") && (parseFloat(document.getElementById("MAmt").value) != 0))
		calculateMonthlyAPR();
    }
}