/usr/include/shogun/distance/CosineDistance.h is in libshogun-dev 1.1.0-4ubuntu2.
This file is owned by root:root, with mode 0o644.
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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) 2008-2009 Christian Gehl
* Copyright (C) 2008-2009 Fraunhofer Institute FIRST
*/
#ifndef _COSINEDISTANCE_H___
#define _COSINEDISTANCE_H___
#include <shogun/lib/common.h>
#include <shogun/distance/SimpleDistance.h>
#include <shogun/features/SimpleFeatures.h>
namespace shogun
{
/** @brief class CosineDistance
*
* The Cosine distance is obtained by using the Cosine similarity (Orchini
* similarity, angular similarity, normalized dot product), which
* measures similarity between two vectors by finding their angle.
* An extension to the Cosine similarity yields the Tanimoto coefficient.
*
* \f[\displaystyle
* d(\bf{x},\bf{x'}) = 1 - \frac{\sum_{i=1}^{n}\bf{x_{i}}\bf{x'_{i}}}
* {\sqrt{\sum_{i=1}^{n} x_{i}^2 \sum_{i=1}^{n} {x'}_{i}^2}} \quad x,x' \in R^{n}
* \f]
*
* @see <a href="http://en.wikipedia.org/wiki/Cosine_similarity"> Wikipedia:
* Cosine similarity </a>
* @see CTanimotoDistance
*/
class CCosineDistance: public CSimpleDistance<float64_t>
{
public:
/** default constructor */
CCosineDistance();
/** constructor
*
* @param l features of left-hand side
* @param r features of right-hand side
*/
CCosineDistance(CSimpleFeatures<float64_t>* l, CSimpleFeatures<float64_t>* r);
virtual ~CCosineDistance();
/** init distance
*
* @param l features of left-hand side
* @param r features of right-hand side
* @return if init was successful
*/
virtual bool init(CFeatures* l, CFeatures* r);
/** cleanup distance */
virtual void cleanup();
/** get distance type we are
*
* @return distance type COSINE
*/
virtual EDistanceType get_distance_type() { return D_COSINE; }
/** get name of the distance
*
* @return name Cosine distance
*/
virtual const char* get_name() const { return "CosineDistance"; }
protected:
/// compute distance for features a and b
/// idx_{a,b} denote the index of the feature vectors
/// in the corresponding feature object
virtual float64_t compute(int32_t idx_a, int32_t idx_b);
};
} // namespace shogun
#endif /* _COSINEDISTANCE_H___ */
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