new methods, v004

README.md

@@ -2,13 +2,22 @@
 
 more functions will be added soon
 
+#### New in version 0.0.4
+
+   1. Amortization tables
+   2. efective_given_nominal_due(nominal_rate, term)
+   3. efective_given_nominal_antipipated
+   4. nominal_antipiated_given_efective
+   5. nominal_due_given_efective
+   6. anticipated_fixed_payment
+
 #### New in version 0.0.3
 
    1. future_given_present
    2. present_given_future
    3. annuity_given_present
    4. annuity_given_future
-   5. present_given_annuity(
+   5. present_given_annuity
    6. future_given_annuity
 
 #### Pending
@@ -42,7 +51,7 @@ A credit in a period of 15 years, the amount is $100.000.000 and the interest is
 call the method following the next instruction.
 
 ```ruby
-fixed_payment_equity(15,100000000,0.0144594763)
+variable_payment_amortization(15,100000000,0.0144594763)
 ```
 The result is a hash with the plan of payments, it looks like that
 
@@ -54,14 +63,22 @@ The result is a hash with the plan of payments, it looks like that
 	.
 	]
 
-The lists of the methods and they params
+The lists of the methods and their params
 
   future_given_present(present_value, interest, term)
   present_given_future(future_value, interest, term)
   annuity_given_present(present_value, interest, term)
   annuity_given_future(future_value, interest, term)
   present_given_annuity(annuity, interest, term)
   future_given_annuity(annuity, interest, term)
+  efective_given_nominal_due(nominal_rate, term)
+  efective_given_nominal_antipipated(nominal_rate, term)
+  nominal_antipiated_given_efective(nominal_rate, term)
+  nominal_due_given_efective(nominal_rate, term)
+  anticipated_fixed_payment(present_value, rate, term)
+
+  variable_payment_amortization(periods, amount, rate)
+  fixed_payment_amortization(periods, amount, rate, payment)
 
 ## Contributing
 

lib/financial_maths.rb

@@ -2,14 +2,14 @@
 
 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
@@ -22,40 +22,80 @@ def fixed_payment_equity(year, amount, year_interest)
     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
 
 

lib/financial_maths/version.rb

@@ -1,3 +1,3 @@
 module FinancialMaths
-  VERSION = "0.0.3"
+  VERSION = "0.0.4"
 end