DiagKernel.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 _DIAGKERNEL_H___
#define _DIAGKERNEL_H___

#include <shogun/lib/common.h>
#include <shogun/kernel/Kernel.h>

namespace shogun
{
class CDiagKernel: public CKernel
{
    public:
        CDiagKernel();

        CDiagKernel(int32_t size, float64_t diag=1.0);

        CDiagKernel(CFeatures* l, CFeatures* r, float64_t diag=1.0);

        virtual ~CDiagKernel();

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

        inline virtual EFeatureType get_feature_type()
        {
            return F_ANY;
        }

        inline virtual EFeatureClass get_feature_class()
        {
            return C_ANY;
        }

        virtual EKernelType get_kernel_type() { return K_DIAG; }

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

    protected:
        inline virtual float64_t compute(int32_t idx_a, int32_t idx_b)
        {
            if (idx_a==idx_b)
                return diag;
            else
                return 0;
        }
    private:
        void init();

    protected:
        float64_t diag;
};
}
#endif /* _DIAGKERNEL_H__ */