/usr/include/shogun/kernel/SphericalKernel.h is in libshogun-dev 1.1.0-4ubuntu2.
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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 | /*
* 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.
*
* Based on GaussianKernel, Written (W) 1999-2010 Soeren Sonnenburg
* Written (W) 2011 Shashwat Lal Das
* Copyright (C) 2011 Berlin Institute of Technology and Max-Planck-Society
*/
#include <shogun/lib/config.h>
#ifndef _SPHERICALKERNEL_H__
#define _SPHERICALKERNEL_H__
#include <shogun/lib/common.h>
#include <shogun/kernel/Kernel.h>
#include <shogun/distance/Distance.h>
namespace shogun
{
class CDistance;
/** @brief Spherical kernel
*
* Formally described as
*
* \f[
* k(x, y) = 1 - \frac{3}{2} \frac{|x-y|}{\sigma}
* + \frac{1}{2} \left( \frac{|x-y|}{\sigma} \right)^3
* \mbox{if}~ |x-y| \leq \sigma \mbox{, zero otherwise}
* \f]
*
*/
class CSphericalKernel: public CKernel
{
public:
/** default constructor */
CSphericalKernel();
/** constructor
*
* @param size cache size
* @param sigma kernel parameter sigma
* @param dist distance
*/
CSphericalKernel(int32_t size, float64_t sigma, CDistance* dist);
/** constructor
*
* @param l features of left-side
* @param r features of right-side
* @param sigma kernel parameter sigma
* @param dist distance
*/
CSphericalKernel(CFeatures *l, CFeatures *r, float64_t sigma, CDistance* dist);
/** initialize kernel with features
*
* @param l features of left-side
* @param r features of right-side
* @return true if successful
*/
virtual bool init(CFeatures* l, CFeatures* r);
void init();
/**
* @return kernel type
*/
inline virtual EKernelType get_kernel_type() { return K_SPHERICAL; }
/**
* @return type of features
*/
inline virtual EFeatureType get_feature_type() { return distance->get_feature_type(); }
/**
* @return class of features
*/
inline virtual EFeatureClass get_feature_class() { return distance->get_feature_class(); }
/**
* @return name of kernel
*/
inline virtual const char* get_name() const { return "SphericalKernel"; }
/** set the kernel's sigma
*
* @param s kernel sigma
*/
inline virtual void set_sigma(float64_t s)
{
sigma=s;
}
/** return the kernel's sigma
*
* @return kernel sigma
*/
inline virtual float64_t get_sigma() const
{
return sigma;
}
virtual ~CSphericalKernel();
protected:
/** distance */
CDistance* distance;
/** width */
float64_t sigma;
/**
* compute kernel function for features a and b
* idx_{a,b} denote the index of the feature vectors
* in the corresponding feature object
*
* @param idx_a index a
* @param idx_b index b
* @return computed kernel function at indices a,b
*/
virtual float64_t compute(int32_t idx_a, int32_t idx_b);
};
}
#endif /* _SPHERICALKERNEL_H__ */
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