Bessel Kernel

src/libshogun/kernel/BesselKernel.cpp

@@ -0,0 +1,63 @@
+#include "BesselKernel.h"
+#include "lib/Mathematics.h"
+#include <math.h>
+
+using namespace shogun;
+
+CBesselKernel::CBesselKernel():CKernel(0),distance(NULL)
+{
+	init();
+	set_sigma(1.0);
+}
+
+CBesselKernel::CBesselKernel(int32_t cache, float64_t sigma, CDistance* dist)
+: CKernel(cache), distance(dist), sigma(sigma)
+{
+	init();
+	ASSERT(distance);
+	SG_REF(distance);
+}
+
+CBesselKernel::CBesselKernel(CFeatures *l, CFeatures *r, float64_t sigma, CDistance* dist)
+: CKernel(10), distance(dist), sigma(sigma)
+{
+	init();
+	ASSERT(distance);
+	SG_REF(distance);
+	init(l, r);
+}
+
+CBesselKernel::~CBesselKernel()
+{
+	cleanup();
+	SG_UNREF(distance);
+}
+
+
+bool CBesselKernel::init(CFeatures* l, CFeatures* r)
+{
+
+	CKernel::init(l,r);
+	distance->init(l,r);
+	return init_normalizer();
+}
+
+void CBesselKernel::load_serializable_post(void) throw (ShogunException)
+{
+	CKernel::load_serializable_post();
+}
+
+
+void CBesselKernel::init()
+{
+        ASSERT(distance);
+	m_parameters->add(&sigma, "sigma", "Sigma kernel parameter.");
+	m_parameters->add((CSGObject**) &distance, "distance", "Distance to be used.");
+}
+
+float64_t CBesselKernel::compute(int32_t idx_a, int32_t idx_b)
+{
+	float64_t dist = distance->distance(idx_a, idx_b);
+	return -j1(sigma*(dist*dist));
+}
+

src/libshogun/kernel/BesselKernel.h

@@ -0,0 +1,124 @@
+/*
+ * 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 Tanmoy Mukherjee
+ * Copyright (C) 2007-2011 Fraunhofer Institute FIRST and Max-Planck-Society
+ * Copyright (C) 2011 IIIT Hyderabad
+ */
+
+#include "lib/config.h"
+
+#ifndef BESSELKERNEL_H_
+#define BESSELKERNEL_H_
+
+#include "lib/common.h"
+#include "kernel/Kernel.h"
+#include "distance/Distance.h"
+
+namespace shogun { 
+
+class CDistance;
+/**  Bessel kernel
+ *
+ *  It is described as
+ *
+ * \f[
+ * 		K(x,x') = -Bessel^{n}_{nu+1}{1}{\sigma*\|x-x'\|^2}
+ * \f]
+ *
+ */
+
+
+class CBesselKernel: public CKernel
+{
+
+   public:
+    /** Default Constructor */      
+   CBesselKernel();
+   /** constructor
+	 * 
+	 * @param size cache size
+	 * @param sigma kernel parameter sigma
+	 * @param dist distance
+	 */   
+
+   CBesselKernel(int32_t size, 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
+	 */
+
+  CBesselKernel(CFeatures *l, CFeatures *r, float64_t coef, CDistance* dist);
+  /** initialize kernel with features
+	 * @param l features left-side
+	 * @param r features right-side
+	 * @return true if successful
+	 */
+
+   virtual bool init(CFeatures* l, CFeatures* r);
+
+
+
+
+   inline virtual EKernelType get_kernel_type() { return K_BESSEL; }
+
+   /**
+   * @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 "Bessel"; }
+
+   inline virtual void set_sigma(float64_t s)
+	{
+	  	sigma=s;
+	}
+
+   virtual ~CBesselKernel();
+
+
+   protected:
+   /// distance to be used
+	CDistance* distance;
+
+	/// sigma parameter of kernel
+	float64_t sigma;
+
+	/**
+	 * compute kernel for specific feature vectors
+	 * corresponding to [idx_a] of left-side and [idx_b] of right-side
+	 * @param idx_a left-side index
+	 * @param idx_b right-side index
+	 * @return kernel value
+	 */
+	virtual float64_t compute(int32_t idx_a, int32_t idx_b);
+
+        /** Can (optionally) be overridden to post-initialize some
+	 *  member variables which are not PARAMETER::ADD'ed.  Make
+	 *  sure that at first the overridden method
+	 *  BASE_CLASS::LOAD_SERIALIZABLE_POST is called.
+	 *
+	 *  @exception ShogunException Will be thrown if an error
+	 *                             occurres.
+	 */
+	virtual void load_serializable_post(void) throw (ShogunException);
+
+    private:
+          void init();
+
+};
+}    
+#endif /* BESSELKERNEL_H_ */