');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.years.value == null || form.years.value.length == 0) || (form.interest.value == null || form.interest.value.length == 0) || (form.principal.value == null || form.principal.value.length == 0)) { return; }
var payments = form.years.value; payments = payments * 12; if (!checkNumber(form.years, 1, 40, "# of Years") || !checkNumber(form.interest, .001, 99, "Interest") || !checkNumber(form.principal, 100, 10000000, "Principal"))
{ form.years.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 < payments; j++)
pow = pow * (1 + i); form.payment.value = (form.principal.value * pow * i) / (pow - 1)
} function clearForm(form)
{ form.years.value = ""; form.interest.value = ""; form.principal.value = ""; }
document.write('
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');document.write('