README.md in danica-1.0.0 vs README.md in danica-1.1.0

@@ -34,32 +34,36 @@
 ### Sample
 
 ```ruby
 class Danica::Function
   class Spatial < Danica::Function
-    attr_accessor :time, :acceleration, :initial_space, :initial_velocity
-    delegate :to_tex, to: :sum
+    variables :time, :acceleration, :initial_space, :initial_velocity
+    delegate :to_tex, :to_gnu, to: :sum
 
     private
 
     def sum
-      @sum ||= Sum.new(variables: parcels)
+      @sum ||= Sum.new(parcels)
     end
 
     def parcels
       [
         initial_space,
         spatial_velocity,
         spatial_acceleration
       ]
     end
 
+    def spatial_velocity
+      Product.new(initial_velocity, time)
+    end
+
     def spatial_acceleration
-      Division.new(numerator: Product.new(variables: [ acceleration, time_squared ]), denominator: 2)
+      Division.new(Product.new(acceleration, time_squared), 2)
     end
 
     def time_squared
-      Power.new(base: time, exponent: 2)
+      Power.new(time, 2)
     end
   end
 end
 
 fx = Danica::Function.new(