SigmoidKernel.h

// SigmoidKernel.h:
// ----------------
//

#ifndef __IPSDKMATH_SIGMOIDKERNEL_H__
#define __IPSDKMATH_SIGMOIDKERNEL_H__

#include <IPSDKMath/IPSDKMathExports.h>
#include <IPSDKUtil/Tools/ForceInline.h>
#include <IPSDKMath/Clustering/ClusteringTypes.h>
#include <IPSDKMath/LinearAlgebra/LinearAlgebraUtils.h>

namespace ipsdk {
namespace math {
namespace clustering {
    

class IPSDKMATH_API SigmoidKernel
{
protected:
    SigmoidKernel(const ipReal64 gamma,
                  const ipReal64 theta);

public:
    ~SigmoidKernel();

// methods
public:
    static SigmoidKernel        createKernel(const ipReal64 gamma,
                                             const ipReal64 theta);

// methods
public:
    inline ipReal64             getGamma() const
    {
        return _gamma;
    }

    inline ipReal64             getTheta() const
    {
        return _theta;
    }

    IPSDK_FORCEINLINE ipReal64  value(const Vector& v) const
    {
        return value(v, v);
    }

    IPSDK_FORCEINLINE ipReal64  value(const Vector& v0,
                                      const Vector& v1) const
    {
        // compute dot product between elements
        const ipReal64 dotProd = boost::numeric::ublas::inner_prod(v0, v1);

        return std::tanh(_gamma*dotProd + _theta);
    }

// attributes
protected:
    ipReal64        _gamma;

    ipReal64        _theta;
};


} // end of namespace clustering
} // end of namespace math
} // end of namespace ipsdk

#endif // __IPSDKMATH_SIGMOIDKERNEL_H__