function createnumber(num,i,s)
{
s = Math.floor(num)%10+(s+'');
 if(num>10)
 {
   if(i>0 && (i%3==0))s=","+s;
 s=createnumber(num/10,i+1,s);
 }
return s;
}

function readblv(num)
{
n=Math.round(num*100);
d2=Math.floor(n%10);
d1=Math.floor((n%100)/10);
return "$ "+createnumber(num,1,".")+d1+d2
}

function licalculate(form)
{
var liamount = parseFloat(form.elements['liamount'].value);
var liinterest = parseFloat(form.elements['liinterest'].value);
var lilenght = parseFloat(form.elements['lilenght'].value);
var liinflation = parseFloat(form.elements['liinflation'].value);     
liinterest = liinterest - liinflation;
var k = 1/(1+liinterest);
var sigma = 1;
 for(var i=0;i<lilenght;i++) sigma = sigma * k;

document.getElementById('lires').innerHTML = readblv(liamount*(1-sigma)/liinterest);
}