lib/dydx/algebra/set/cos.rb in dydx-0.0.1 vs lib/dydx/algebra/set/cos.rb in dydx-0.0.2

@@ -10,12 +10,13 @@
 
         def to_s
           "cos( #{x.to_s} )"
         end
 
-        def d(sym=:x)
+        def differentiate(sym=:x)
           -1 * sin(x) * x.d(sym)
         end
+        alias_method :d, :differentiate
       end
     end
   end
 end
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