lib/dydx/algebra/inverse.rb in dydx-0.1.3 vs lib/dydx/algebra/inverse.rb in dydx-0.1.4

@@ -13,15 +13,29 @@
         when :+ then "( - #{x} )"
         when :* then "( 1 / #{x} )"
         end
       end
 
-      def differentiate(sym=:x)
+      def subst(hash = {})
         case operator
+        when :+ then x.subst(hash) * -1
+        when :* then x.subst(hash) ** -1
+        end
+      end
+
+      def to_f
+        case operator
+        when :+ then x.to_f * -1
+        when :* then x.to_f ** -1
+        end
+      end
+
+      def differentiate(sym = :x)
+        case operator
         when :+
           inverse(x.differentiate(sym), :+)
         when :*
-          inverse(x.differentiate(sym) * inverse(x ^ 2, :*), :+)
+          inverse(x.differentiate(sym) * inverse(x ** 2, :*), :+)
         end
       end
       alias_method :d, :differentiate
     end
   end