SHOGUN v0.9.0
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00001 /* 00002 * This program is free software; you can redistribute it and/or modify 00003 * it under the terms of the GNU General Public License as published by 00004 * the Free Software Foundation; either version 3 of the License, or 00005 * (at your option) any later version. 00006 * 00007 * Written (W) 2008-2009 Soeren Sonnenburg 00008 * Copyright (C) 2008-2009 Fraunhofer Institute FIRST and Max-Planck-Society 00009 */ 00010 00011 #include "lib/common.h" 00012 #include "kernel/GaussianShortRealKernel.h" 00013 #include "features/Features.h" 00014 #include "features/SimpleFeatures.h" 00015 #include "lib/io.h" 00016 00017 using namespace shogun; 00018 00019 CGaussianShortRealKernel::CGaussianShortRealKernel(void) 00020 : CDotKernel(0), width(0.0) 00021 { 00022 SG_UNSTABLE("CGaussianShortRealKernel::" 00023 "CGaussianShortRealKernel(void)", "\n"); 00024 } 00025 00026 CGaussianShortRealKernel::CGaussianShortRealKernel(int32_t size, float64_t w) 00027 : CDotKernel(size), width(w) 00028 { 00029 } 00030 00031 CGaussianShortRealKernel::CGaussianShortRealKernel( 00032 CSimpleFeatures<float32_t>* l, CSimpleFeatures<float32_t>* r, float64_t w, int32_t size) 00033 : CDotKernel(size), width(w) 00034 { 00035 init(l,r); 00036 } 00037 00038 CGaussianShortRealKernel::~CGaussianShortRealKernel() 00039 { 00040 } 00041 00042 bool CGaussianShortRealKernel::init(CFeatures* l, CFeatures* r) 00043 { 00044 CDotKernel::init(l, r); 00045 return init_normalizer(); 00046 } 00047 00048 float64_t CGaussianShortRealKernel::compute(int32_t idx_a, int32_t idx_b) 00049 { 00050 int32_t alen, blen; 00051 bool afree, bfree; 00052 00053 float32_t* avec=((CSimpleFeatures<float32_t>*) lhs)->get_feature_vector(idx_a, alen, afree); 00054 float32_t* bvec=((CSimpleFeatures<float32_t>*) rhs)->get_feature_vector(idx_b, blen, bfree); 00055 ASSERT(alen==blen); 00056 00057 float64_t result=0; 00058 for (int32_t i=0; i<alen; i++) 00059 result+=CMath::sq(avec[i]-bvec[i]); 00060 00061 result=exp(-result/width); 00062 00063 ((CSimpleFeatures<float32_t>*) lhs)->free_feature_vector(avec, idx_a, afree); 00064 ((CSimpleFeatures<float32_t>*) rhs)->free_feature_vector(bvec, idx_b, bfree); 00065 00066 return result; 00067 }