<!--

window.defaultStatus = "Many thanks to Niksun for assistance";

function calculate(form) {
   var type = form.type.value;
   var varb = form.varb.value;
   var i = "" + form.i.value || "0";
   var c = ""+ form.c.value || "0";
   if (form.FV) {
     var FV = ""+ form.FV.value || "0";
     FV = format(FV);
     form.FV.value = FV;
   }
   if (form.A) {
     var A = ""+ form.A.value || "0";
     A = format(A);
     form.A.value = A;
   }
   if (form.p) {
     var p = ""+ form.p.value || "0";
     p = format(p)
     form.p.value = p;
   }
   if (form.n) {
     var n = ""+ form.n.value || "0";
     n = format(n);
     form.n.value = n;
   }
   i = format(i);
   form.i.value = i;
   c = format(c);
   form.c.value = c;

   n = n * c;

   if (i <= 0) {
      alert("Please enter a valid interest rate:");
      form.i.select();
      form.i.focus();
      return;
   }
   if (i.charAt(i.length - 1) == "%") {
      i = i.substring(0,i.length - 1);
      form.i.value = i;
   }
   if (i >= 1) {
      i = i / 100;
      form.i.value = i;
   }
   i = "" + i;
   if (i.indexOf(".") != 0) {
      i = i.substring(i.indexOf("."),i.length);
   }

   if (c <= 0) {
      alert("Please enter a valid # of times your investment is compounded each year:");
      form.c.select();
      form.c.focus();
      return;
   }

   if (type == "annuity") {
      p = (p * 12) / c;
      if (varb == "FV") {
         if (form.p.value <= 0) {
            alert("Please enter a valid monthly investment:");
            form.p.select();
            form.p.focus();
            return;
         } else if (form.n.value <= 0) {
            alert("Please enter a valid # of years:");
            form.n.select();
            form.n.focus();
            return;
         }
         FV = (p * (Math.pow((1 + i/c),n) - 1)) / (i/c);
         FV = "$" + FV;
         FV = (FV.indexOf(".") >= 0) ? FV.substring(0, FV.indexOf(".",1) + 3) : FV + ".00";
         answer(form,FV);
         return;
      } else if (varb == "p") {
         if (form.FV.value <= 0) {
            alert("Please enter a valid future value:");
            form.FV.select();
            form.FV.focus();
            return;
         } else if (form.n.value <= 0) {
            alert("Please enter a valid # of years:");
            form.n.select();
            form.n.focus();
            return;
         }
         p = (FV * i) / ((Math.pow((1 + i/c),n) - 1) * c)
         p = (p * c) / 12;
         p = "$" + p;
         p = (p.indexOf(".") >= 0) ? p.substring(0, p.indexOf(".",1) + 3) : p + ".00";
         answer(form,p);
         return;
      } else if (varb == "n") {
         if (form.FV.value <= 0) {
            alert("Please enter a valid future value:");
            form.FV.select();
            form.FV.focus();
            return;
         } else if (form.p.value <= 0) {
            alert("Please enter a valid monthly investment:");
            form.p.select();
            form.p.focus();
            return;
         }
         n = (Math.log(FV * i + c * p) - Math.log(c * p)) / (Math.log(c + i) - Math.log(c));
         n = n / c;
         n = "" + n;
         n = (n.indexOf(".") >= 0) ? n.substring(0, n.indexOf(".",1) + 3) : n + ".00";
         answer(form,n);
         return;
      }
   } else {
      if (varb == "FV") {
         if (form.A.value <= 0) {
            alert("Please enter a valid investment:");
            form.A.select();
            form.A.focus();
            return;
         } else if (form.n.value <= 0) {
            alert("Please enter a valid # of years:");
            form.n.select();
            form.n.focus();
            return;
         }
         FV = A * Math.pow((1 + i/c),n);
         FV = "$" + FV;
         FV = (FV.indexOf(".") >= 0) ? FV.substring(0, FV.indexOf(".",1) + 3) : FV + ".00";
         answer(form,FV);
         return;
      } else if (varb == "A") {
         if (form.FV.value <= 0) {
            alert("Please enter a valid future value:");
            form.FV.select();
            form.FV.focus();
            return;
         } else if (form.n.value <= 0) {
            alert("Please enter a valid # of years:");
            form.n.select();
            form.n.focus();
            return;
         }
         A = FV / Math.pow((1 + i/c),n);
         A = "$" + A;
         A = (A.indexOf(".") >= 0) ? A.substring(0, A.indexOf(".",1) + 3) : A + ".00";
         answer(form,A);
         return;
      } else if (varb == "n") {
         if (form.FV.value <= 0) {
            alert("Please enter a valid future value:");
            form.FV.select();
            form.FV.focus();
            return;
         } else if (form.A.value <= 0) {
            alert("Please enter a valid investment:");
            form.A.select();
            form.A.focus();
            return;
         }
         n = (Math.log(FV) - Math.log(A)) / (Math.log(c + i) - Math.log(c));
         n = n / c;
         n = "" + n;
         n = (n.indexOf(".") >= 0) ? n.substring(0, n.indexOf(".",1) + 3) : n + ".00";
         answer(form,n);
         return;
      }
   }
}

function format(y) {
  while (y.indexOf(",") >= 1) {
    x = y.indexOf(",");
    y = y.substring(0, x) + y.substring(x + 1, y.length);
  }
  return y;
}

function answer(form,x) {
  form.answer.value = x;
  form.answer.focus();
  form.answer.select();
}

// -->