LinearKernel.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) 1999-2010 Soeren Sonnenburg
 * Copyright (C) 1999-2009 Fraunhofer Institute FIRST and Max-Planck-Society
 * Copyright (C) 2010 Berlin Institute of Technology
 */

#ifndef _LINEARKERNEL_H___
#define _LINEARKERNEL_H___

#include <shogun/lib/common.h>
#include <shogun/kernel/DotKernel.h>
#include <shogun/features/DotFeatures.h>
#include <shogun/machine/KernelMachine.h>

namespace shogun
{
    class CKernelMachine;
    class CDotFeatures;

class CLinearKernel: public CDotKernel
{
    public:
        CLinearKernel();

        CLinearKernel(CDotFeatures* l, CDotFeatures* r);

        virtual ~CLinearKernel();

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

        virtual void cleanup();

        virtual EKernelType get_kernel_type() { return K_LINEAR; }

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

        virtual bool init_optimization(
            int32_t num_suppvec, int32_t* sv_idx, float64_t* alphas);

        virtual bool init_optimization(CKernelMachine* km);

        virtual bool delete_optimization();

        virtual float64_t compute_optimized(int32_t idx);

        virtual void clear_normal()
        {
            normal = SGVector<float64_t>(((CDotFeatures*)lhs)->get_dim_feature_space());
            normal.zero();
            set_is_initialized(true);
        }

        virtual void add_to_normal(int32_t idx, float64_t weight);

        SGVector<float64_t> get_w() const 
        {
            ASSERT(lhs);
            return normal;
        }

        void set_w(SGVector<float64_t> w)
        {
            ASSERT(lhs && w.size()==((CDotFeatures*) lhs)->get_dim_feature_space());
            this->normal = w;
        }

    protected:
        SGVector<float64_t> normal;
};
}
#endif /* _LINEARKERNEL_H__ */