#pragma once

#include <cmath>

#include "./StreamingActivationFunction.h"
#include "../../sse_mathfun.h"

namespace NeuralNetwork {
namespace ActivationFunction {

	/**
	* @author Tomas Cernik (Tom.Cernik@gmail.com)
	* @brief Class for computing sigmoid
	*/
	class Sigmoid: public StreamingActivationFunction {
		public:
			Sigmoid(const float lambdaP = -0.5): lambda(lambdaP) {}
			inline virtual float derivatedOutput(const float&,const float &output) override { return lambda*output*(1.0f-output); }
			inline virtual float operator()(const float &x) override { return 1.0f / (1.0f +exp(lambda*x) ); };
			inline virtual __m128 operator()(const __m128 &x) override {
				// exp_ps is extremly slow!
				return _mm_div_ps(_mm_set1_ps(1.0),_mm_add_ps(exp_ps(_mm_mul_ps(_mm_set1_ps(lambda),x)),_mm_set1_ps(1.0)));
			}
			virtual ActivationFunction* clone() const override {
				return new Sigmoid(lambda);
			}

			virtual std::string stringify() const override {
				return "{ \"class\": \"NeuralNetwork::ActivationFunction::Sigmoid\", \"lamba\" : "+std::to_string(lambda)+"}";
			}
		protected:
			float lambda;
	};
}
}