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00011 #include <shogun/lib/common.h>
00012 #include <shogun/kernel/GaussianShortRealKernel.h>
00013 #include <shogun/features/Features.h>
00014 #include <shogun/io/SGIO.h>
00015
00016 using namespace shogun;
00017
00018 CGaussianShortRealKernel::CGaussianShortRealKernel()
00019 : CDotKernel(0), width(0.0)
00020 {
00021 register_params();
00022 }
00023
00024 CGaussianShortRealKernel::CGaussianShortRealKernel(int32_t size, float64_t w)
00025 : CDotKernel(size), width(w)
00026 {
00027 register_params();
00028 }
00029
00030 CGaussianShortRealKernel::CGaussianShortRealKernel(
00031 CDenseFeatures<float32_t>* l, CDenseFeatures<float32_t>* r, float64_t w, int32_t size)
00032 : CDotKernel(size), width(w)
00033 {
00034 init(l,r);
00035 register_params();
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=((CDenseFeatures<float32_t>*) lhs)->get_feature_vector(idx_a, alen, afree);
00054 float32_t* bvec=((CDenseFeatures<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 ((CDenseFeatures<float32_t>*) lhs)->free_feature_vector(avec, idx_a, afree);
00064 ((CDenseFeatures<float32_t>*) rhs)->free_feature_vector(bvec, idx_b, bfree);
00065
00066 return result;
00067 }
00068
00069 void CGaussianShortRealKernel::register_params()
00070 {
00071 SG_ADD(&width, "width", "kernel width", MS_AVAILABLE);
00072 }