function checkNumber(input, min, max, msg) {

        msg = msg + " field has invalid data: " + input.value;

        var str = input.value;
        for (var i = 0; i < str.length; i++) {
            var ch = str.substring(i, i + 1)
            if ((ch < "0" || "9" < ch) && ch != '.') {
                alert(msg);
                return false;
            }
        }
        var num = 0 + str
        if (num < min || max < num) {
            alert(msg + " not in range [" + min + ".." + max + "]");
            return false;
        }
        input.value = str;
        return true;
    }

    function computeField(input) {

        if (input.value != null && input.value.length != 0)
            input.value = "" + eval(input.value);
        computeForm(input.form);
    }

    function computeForm(form) {

        if ((form.payments.value == null || form.payments.value.length == 0) ||
            (form.interest.value == null || form.interest.value.length == 0) ||
            (form.principal.value == null || form.principal.value.length == 0)) {
            return;
        }

        if (!checkNumber(form.payments, 1, 480, "# of payments") ||
            !checkNumber(form.interest, .001, 99, "% Interest") ||

            !checkNumber(form.principal, 100, 10000000, "Principal")) {
            form.payment.value = "Invalid";
            return;
        }

        var i = form.interest.value;
        
       if (i >= 1.0) {
            i = i / 100.0;
           // form.interest.value = i;
        }
        i /= 12;

        var pow = 1;
        for (var j = 0; j < form.payments.value; j++)
            pow = pow * (1 + i);
        form.payment.value = floor((form.principal.value * pow * i) / (pow - 1))
    }

    function clearForm(form) {
        form.payments.value = "";
        form.interest.value = "";
        form.principal.value = "";
    }
    function floor(number)
{
  return Math.floor(number*Math.pow(10,2))/Math.pow(10,2);
}

function dosum()
{
  var mi = document.temps.IR.value / 1200;
  var base = 1;
  var mbase = 1 + mi;
  for (i=0; i<document.temps.YR.value * 12; i++)
  {
    base = base * mbase
  }
  document.temps.PI.value = floor(document.temps.LA.value * mi / ( 1 - (1/base)))
  document.temps.MT.value = floor(document.temps.AT.value / 12)
  document.temps.MI.value = floor(document.temps.AI.value / 12)
  var dasum = document.temps.LA.value * mi / ( 1 - (1/base)) +
	document.temps.AT.value / 12 + 
	document.temps.AI.value / 12;
  document.temps.MP.value = floor(dasum);
}