function clear_Click(){
  document.analyzer.loan.value = "";
  document.analyzer.downp.value="";
  document.analyzer.term.value = "";
  document.analyzer.rate.value = "";
  document.analyzer.extra.value = "";
  document.analyzer.thedown.value="";
  document.analyzer.payment.value = "";
  document.analyzer.payback.value = "";
  document.analyzer.totalintrest.value = "";
  document.analyzer.xtotal.value = "";
  document.analyzer.xinterest.value = "";
  document.analyzer.savings.value = "";
  document.analyzer.xmonths.value = "";
}

function calculate_Click(){
  var t1=0.0;
  var t=0.0;
  var i=0.0;
  var l=0.0;
  var x=0.0;
  var b=0.0;
  var t2=0.0;
  var im=0.0;
  var d=0.0;
  var n=0.0
  var p=0.0;
  var ia=0.0;
  var ip=0.0;
  var pp=0.0;
  var xpt=0.0;
  var dn=0.0;
  l = document.analyzer.loan.value;
  if (l=="") {
   alert ("A loan amount must be entered.");
   document.analyzer.loan.focus()
  }

  t = document.analyzer.term.value;
  if (t=="") {
   alert ("The loan's term in years must be entered.");
   document.analyzer.term.focus()
  }
  i = document.analyzer.rate.value;
  if (i=="") {
   alert ("The interest rate must be entered.");
   document.analyzer.rate.focus()
  }
  x = document.analyzer.extra.value;
  if (x=="") {
    x = 0
  }
  dn = document.analyzer.downp.value;
  if (dn=="") {
      dn = 0
  }

  if (dn > 0) {
     dn = dn/100;
     dn = l*dn;
  }
  document.analyzer.thedown.value = dn;
  b = l-dn;
  i = i/100;
  im = i/12;
  m = t*12;
  t2 = 1+im;
  t1 = Math.pow(t2, m);
  n = im*t1;
  d = t1-1;
  p = b*(n/d);
  t1 = p*100;
  t1 = Math.round(t1);
  p = t1/100;

  document.analyzer.payment.value = p;

  pt = p*m;
  pt = pt*100;
  pt = Math.round(pt);
  pt = pt/100;
  document.analyzer.payback.value = pt;

  it = pt-l;
  it =it*100;
  it = Math.round(it);
  it = it/100;
  document.analyzer.totalintrest.value = it;

  x = x*100;
  x = Math.round(x);
  x = x/100;

if (x == 0){
  document.analyzer.xtotal.value = "";
  document.analyzer.xinterest.value = "";
  document.analyzer.savings.value= "";
  document.analyzer.xmonths.value="";
}  

if (x < 0){
   alert( "Extra payment must be a positive value")
} 

if (x > 0){

var j
j = 0;
ip = 0;
pp = 0;

l1 = m+1;
//msgvar = "Balance = " + b + " Monthly Interest Rate = " + im + " Extra Pymt =  " + x + " //monthly payment = " + p;
//alert(msgvar);


//  for (k = 0;  k < l1; k++){
while (b > 0) {    
      ia = im*b;
      ip = ip+ia;
      pp = p-ia;
      b = b-pp;
      b = b-x;
      j = j+1;
//msgvar = "Balance = " + b + " Normal Interest = " + ia + " Prin Pymt =  " + pp +   " Acc //Interest " + ip;
//alert (msgvar);

    
  }
  var xpt=0.0;

  xpt = p+x;
  xpt = xpt*j;
  xpt = xpt+b;
  
  xpt = xpt*100;
  xpt = Math.round(xpt);
  xpt = xpt/100;
 
  document.analyzer.xtotal.value = xpt;
  ip = ip*100;
  ip = Math.round(ip);
  ip = ip/100;
  document.analyzer.xinterest.value=ip;

  s = pt - xpt;
  s = s*100;
  s = Math.round(s);
  s = s/100;
document.analyzer.savings.value = s;

document.analyzer.xmonths.value = j;


 // msgvar = "p= " + p + " x = " + x + "  xpt = " + xpt;
 // alert(msgvar);
  }
}