Neuron.h

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#ifndef _NEURON_H
#define _NEURON_H

#include "Link.h"
#include "defines.h"
#include <string>

namespace annie
{

// Some activation functions and their derivatives

real identity(real x);
real didentity(real x);
real sigmoid(real x);
real dsigmoid(real x);
real gaussian(real x);
real dgaussian(real x);
real signum(real x);
real tansig(real x);
real dtansig(real x);



typedef real(*ActivationFunction)(real);

typedef std::vector<Link *> LINKS;

class Neuron
{
protected:
    int _label;

    mutable bool _outputCacheValid;

    mutable real _activationCache;
    mutable real _outputCache;

    mutable bool _errorCacheValid;

    mutable real _errorCache;

    std::vector<char *> _classHeirarchy;

    LINKS _inputLinks;
public:
    LINKS _outputLinks;
protected:
    ActivationFunction _activationFunction;

    virtual void _recacheOutput() const =0;

    virtual void _recacheError() const =0;

public:
    Neuron(int label);

    Neuron(Neuron &neuron);

    virtual ~Neuron();

    virtual real getActivation() const;

    virtual real getOutput() const;

    virtual real getError() const;

    virtual int getLabel() const;

    virtual uint getInputCount() const;

    virtual uint getOutputCount() const;

    virtual void invalidateOutputCache();

    virtual void invalidateErrorCache();

    virtual int getInputs(std::vector<int> &labels, Vector &weights);

    void getWeights(Vector &out)    const;

    virtual void disconnect(Neuron *from);

    virtual real getWeight(Neuron *from) const;

    virtual operator std::string() const;
    
    virtual const char *getClassName() const=0;
    friend class Link;

    bool instanceOf(const char *className) const;

    friend std::ostream& operator << (std::ostream& s, const Neuron &neuron);
};

}; //namespace annie
#endif // define _NEURON_H

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