function TestaEntrada(form, button) 
 {CalculaTaxa(form); return; }

function CalculaTaxa(form)
 {
 var PVista  = parseFloat(form.Entrada1.value);
 var Njapagas = parseFloat(form.Entrada2.value);
 var R       = parseFloat(form.Entrada3.value);
 var N       = parseFloat(form.Entrada4.value);
 var VFin    = PVista
 if(form.Entrada3.value=="" ||form.Entrada3.value==" " ||form.Entrada3.value=="0" || form.Entrada1.value=="" || form.Entrada1.value==" " || form.Entrada1.value=="0" || form.Entrada2.value=="" || form.Entrada2.value==" " || form.Entrada2.value=="0" || form.Entrada4.value=="" || form.Entrada4.value==" " || form.Entrada4.value=="0")
  {
  alert("Preencha corretamente as caixas. Com os valores atuais das caixas e' impossivel calcular a taxa de juros deste financiamento.");
  return;
  }
 {
 P = VFin
 S = P/R
 T = 1/S -S/N/N
 for ( cont=0; cont<25; cont++)
  {
  A = Math.pow((1+T),N)
  B = Math.pow((1+T),(N+1))
  T = T-(((A-1)/(T*A)-S)*B*T*T)/(1+T*(N+1)-B)
  }
 }
 T = parseInt(T*10E8,10)/10E6;
 SaldoD = P
 for ( cont=1; cont<Njapagas+1; cont++)
  {
   SaldoDevedor = (SaldoD + (SaldoD*(T/100)))-R
   SaldoD = SaldoDevedor
  }
  SaldoDevedor = Math.round(SaldoDevedor*100)/100
  T = Math.round(T*100)/100
 {form.Saida1.value=T, form.Saida2.value=SaldoDevedor;}
return;
}