function calcPayment() {
    var mp, v, i, n;

    if (is.major >= 4) {
        //Replace any commas with a dot.        
        eval("document.CalcPayment.interest.value = document.CalcPayment.interest.value.replace(/,/g, \".\");");
        eval("document.CalcPayment.value.value = document.CalcPayment.value.value.replace(/,/g, \".\");");
        eval("document.CalcPayment.deposit.value = document.CalcPayment.deposit.value.replace(/,/g, \".\");");

        //Replace any spaces with nothing.
        eval("document.CalcPayment.interest.value = document.CalcPayment.interest.value.replace(/ /g, \"\");");
        eval("document.CalcPayment.value.value = document.CalcPayment.value.value.replace(/ /g, \"\");");
        eval("document.CalcPayment.deposit.value = document.CalcPayment.deposit.value.replace(/ /g, \"\");");

    
        var prob;
        eval("prob = document.CalcPayment.value.value.match(/[^0-9\\.]/);");
        if (prob) {
            alert("Please type a valid value.");
            return;
        }
    
        eval("prob = document.CalcPayment.interest.value.match(/[^0-9\\.]/);");
        if (prob) {
            alert("Please type a valid interest rate.");
            return;
        }
    
        eval("prob = document.CalcPayment.deposit.value.match(/[^0-9\\.]/);");
        if (prob) {
            alert("Please type a valid deposit value.");
            return;
        } 
    }

    v = document.CalcPayment.value.value - document.CalcPayment.deposit.value;
    i = document.CalcPayment.interest.value / 1200.0;
    n = document.CalcPayment.years.value * 12.0;
    mp = (v * i) / (1 - 1 / power(1 + i, n));

    if (v < 1 || i == 0 || n < 1) {
        alert("Please enter valid positive numbers!");
        return;
    }
  
    //if (is.ie4up) {
    //    paymentAnswer.innerText = Math.round(mp);
    //}
    //else {	   //Netscape or old IE.
        document.CalcPayment.paymentAnswer.value = Math.round(mp);        
    //}


}