softmax.h

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/*
 * SoftMax.h
 *
 *  Created on: Jul 15, 2019
 *    Author: joseph
 */

#ifndef BLACKCAT_NEURALNETWORK_SOFTMAX_H_
#define BLACKCAT_NEURALNETWORK_SOFTMAX_H_

#include "layer_base.h"

namespace bc {
namespace nn {

template<class SystemTag, class ValueType>
struct SoftMax:
        public Layer_Base<
            SoftMax<SystemTag, ValueType>,
            Tensor_Descriptor<ValueType, SystemTag, Integer<1>>>
{
    using system_tag = SystemTag;
    using value_type = ValueType;

    using input_descriptor_t = Tensor_Descriptor<ValueType, SystemTag, Integer<1>>;
    using parent_type = Layer_Base<SoftMax<SystemTag, ValueType>, input_descriptor_t>;

    using mat = bc::Matrix<ValueType, bc::Allocator<ValueType, SystemTag>>;
    using vec = bc::Vector<ValueType, bc::Allocator<ValueType, SystemTag>>;

private:

    mat y;

public:

    SoftMax(int inputs):
        parent_type(__func__, {inputs}, {inputs}) {}

    template<class Allocator>
    const auto& forward_propagation(const bc::Matrix<value_type, Allocator>& x) {
        for (int i = 0; i < x.cols(); ++i)
            y[i] = bc::exp(x[i]) / bc::tensors::sum(exp(x[i]));

        return y;
    }
    template<class Allocator>
    auto forward_propagation(const bc::Vector<value_type, Allocator>& x) {
        return  bc::exp(x) / bc::tensors::sum(exp(x));
    }


    template<class X, class Matrix>
    auto back_propagation(const X& x, const Matrix& dy) {
        return dy;
    }

    virtual void set_batch_size_hook(int bs) override {
        y = mat(this->output_size(), bs);
    }
};


template<class ValueType, class SystemTag>
SoftMax<SystemTag, ValueType> softmax(SystemTag system_tag, int inputs) {
    return SoftMax<SystemTag, ValueType>(inputs);
}
template<class SystemTag>
auto softmax(SystemTag system_tag, int inputs) {
    return SoftMax<SystemTag, typename SystemTag::default_floating_point_type>(inputs);
}

auto softmax(int inputs) {
    return SoftMax<BLACKCAT_DEFAULT_SYSTEM_T,
            typename BLACKCAT_DEFAULT_SYSTEM_T::default_floating_point_type>(inputs);
}

}
}




#endif /* SOFTMAX_H_ */