BesselKernel.cpp

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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) 2011 Zi Yuan
 * Copyright (C) 2011 Berlin Institute of Technology and Max-Planck-Society
 */

#include <shogun/kernel/BesselKernel.h>
#include <shogun/mathematics/Math.h>
#include <math.h>

using namespace shogun;

CBesselKernel::CBesselKernel():CDistanceKernel(),order(0.0),degree(0)
{
    init();
}

CBesselKernel::CBesselKernel(int32_t size, float64_t v, float64_t w,
        int32_t n, CDistance* dist) :
    CDistanceKernel(size,w,dist), order(v), degree(n)
{
    ASSERT(distance)
    SG_REF(distance);
    init();
}

CBesselKernel::CBesselKernel(CFeatures* l, CFeatures* r, float64_t v,
        float64_t w, int32_t n, CDistance* dist, int32_t size) :
    CDistanceKernel(size,w,dist), order(v), degree(n)
{
    init();
    ASSERT(distance)
    SG_REF(distance);
    init(l,r);
}

CBesselKernel::~CBesselKernel()
{
    cleanup();
    SG_UNREF(distance);
}

void CBesselKernel::cleanup()
{
}

bool CBesselKernel::init(CFeatures* l, CFeatures* r)
{
    ASSERT(distance)
    CDistanceKernel::init(l,r);
    distance->init(l,r);
    return init_normalizer();
}

void CBesselKernel::init()
{
    SG_ADD(&order, "order", "Kernel order.", MS_AVAILABLE);
    SG_ADD(&degree, "degree", "Kernel degree.", MS_AVAILABLE);
}

float64_t CBesselKernel::compute(int32_t idx_a, int32_t idx_b)
{
    float64_t dist = distance->distance(idx_a, idx_b);
    return jn(order,dist/width)/CMath::pow(dist,-degree*order);
}