fixed Sigmoid function and modifications

include/NeuralNetwork/ActivationFunction/ActivationFunction.h

@@ -14,12 +14,21 @@ namespace ActivationFunction {
 
 			virtual ~ActivationFunction() {}
 
+			/**
+			 * @brief Returns derivation of output, it is slower than version with output as it needs to compute output
+			 * @param input is input of function
+			 */
+			inline float derivatedOutput(const float &input) {
+				return derivatedOutput(input,operator()(input));
+			};
+
 			/**
 			 * @brief Returns derivation of output
 			 * @param input is input of function
 			 * @param output is output of function
+			 * @see derivatedOutput
 			 */
-			virtual float derivatedOutput(const float &input,const float &output)=0;
+			virtual float derivatedOutput(const float &input, const float &output) =0;
 
 			/**
 			 * @brief Returns value of output