Chi2Kernel.h

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/*
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 3 of the License, or
 * (at your option) any later version.
 *
 * Written (W) 1999-2009 Soeren Sonnenburg
 * Copyright (C) 1999-2009 Fraunhofer Institute FIRST and Max-Planck-Society
 */

#ifndef _CHI2KERNEL_H___
#define _CHI2KERNEL_H___

#include <shogun/lib/common.h>
#include <shogun/kernel/DotKernel.h>
#include <shogun/features/Features.h>
#include <shogun/features/DenseFeatures.h>

namespace shogun
{
class CChi2Kernel: public CDotKernel
{
    void init();

    public:
        CChi2Kernel();

        CChi2Kernel(int32_t size, float64_t width);

        CChi2Kernel(
            CDenseFeatures<float64_t>* l, CDenseFeatures<float64_t>* r, float64_t width, int32_t size);

        virtual ~CChi2Kernel();

        virtual bool init(CFeatures* l, CFeatures* r);

        virtual float64_t get_width();

        static CChi2Kernel* obtain_from_generic(CKernel* kernel);

        virtual EKernelType get_kernel_type() { return K_CHI2; }

        virtual EFeatureClass get_feature_class() { return C_DENSE; }

        virtual EFeatureType get_feature_type() { return F_DREAL; }

        virtual const char* get_name() const { return "Chi2Kernel"; }

    protected:
        virtual float64_t compute(int32_t idx_a, int32_t idx_b);

    protected:
        float64_t width;
};
}
#endif /* _CHI2KERNEL_H__ */