lib/financial_maths.rb in financial_maths-0.0.3 vs lib/financial_maths.rb in financial_maths-0.0.4

@@ -1,17 +1,17 @@
 require "financial_maths/version"
 
 module FinancialMaths
 
-  def fixed_payment_equity(year, amount, year_interest)
-    years = year*12
-    monthly_payments = amount/years
+  def variable_payment_amortization(periods, amount, rate)
+
+    monthly_payments = amount/periods
     result = []
     result << {:period=> 0, :monthly_payment => nil, :interest => nil, :payment => nil, :balance => amount}
 
-    for i in 1..years
-      interest = amount * year_interest
+    for i in 1..periods
+      interest = amount * rate
       month_payment = monthly_payments + interest
       amount -= monthly_payments
       #date += 1
       result << {:period=> i,
                  :payment => month_payment,
@@ -20,42 +20,82 @@
                  :balance => amount}
     end
     result
   end
 
-  def fixed_payment_amortization(year, amount, year_interest)
+  def fixed_payment_amortization(periods, amount, rate, payment)
+    result = []
+    result << {:period=> 0, :monthly_payment => nil, :interest => nil, :payment => nil, :balance => amount}
 
+    for i in 1..periods
+      interest = amount * rate
+      month_payment = payment - interest
+      amount -= month_payment
+      #date += 1
+      result << {:period=> i,
+                 :payment => payment,
+                 :interest => interest,
+                 :monthly_payment => month_payment,
+                 :balance => amount}
+    end
+    result
   end
 
-  # hallar futuro dado el valor presente
+  # hallar futuro dado el valor presente    HFDP
   def future_given_present(present_value, interest, term)
     (present_value.to_f * (1 + interest.to_f) ** term).round(4)
   end
 
-  # hallar presente dado el futuro
+  # hallar presente dado el futuro          HPDF
   def present_given_future(future_value, interest, term)
     (future_value.to_f / (1 +interest.to_f) ** term).round(4)
   end
 
-  # hallar Anualidad dado el valor presente
+  # hallar Anualidad dado el valor presente    HADP
   def annuity_given_present(present_value, interest, term)
-     (present_value.to_f * ((interest *(1+interest.to_f) ** term) / ((1 + interest.to_f) ** term) -1)).round(4)
+    interest = interest.to_f
+     (present_value.to_f * ((interest * (1+interest) ** term) / (((1 + interest) ** term) -1))).round(4)
   end
 
-  # hallar anualidad dado el valor futuro
+  # hallar anualidad dado el valor futuro      HADF
   def annuity_given_future(future_value, interest, term)
      (future_value.to_f * (interest.to_f / ((1 + interest) ** term)-1)).round(4)
   end
 
-  # hallar presente dado la anualidad
+  # hallar presente dado la anualidad        HPDA
   def present_given_annuity(annuity, interest, term)
     (annuity.to_f * (((1 + interest.to_f) ** term) -1) / (interest.to_f * (1 + interest.to_f) ** term )).round(4)
   end
 
-  # hallar futuro dado la anualidad
+  # hallar futuro dado la anualidad          HFDA
   def future_given_annuity(annuity, interest, term)
     (annuity * (((1 + interest.to_f) ** term) -1) / interest.to_f ).round(4)
   end
+
+  # hallar tasa efectiva dado la tasa nominal vencida  NVEF
+  def efective_given_nominal_due(nominal_rate, term)
+    (((1 + nominal_rate.to_f) ** term)-1).round(4)
+    end
+
+    # hallar tasa efectiva dado la tasa nominal anticipada    NAEF
+    def efective_given_nominal_antipipated(nominal_rate, term)
+      (1 / ((1 -  nominal_rate.to_f) ** term)).round(4) - 1
+    end
+
+    # hallar tasa nominal anticipada dado efectiva   EFNV
+    def nominal_antipiated_given_efective(nominal_rate, term)
+      (1 - (1 / (1 +  nominal_rate.to_f) ** (1 / term))).round(4)
+    end
+
+    # hallar tasa nominal anticipada dado efectiva   EFNV
+    def nominal_due_given_efective(nominal_rate, term)
+      ((nominal_rate.to_f + 1) ** (1 / term)).round(4)
+    end
+    # Hallar la cuota fija anticipada   HCFA
+    def anticipated_fixed_payment(present_value, rate, term)
+      ((present_value.to_f * rate.to_f) / ((rate.to_f + 1) - (1 / (1 + rate) ** (term - 1)))).round(4)
+  end
+
 
 end