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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 }