SigmoidKernel.cpp

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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) 1999-2008 Soeren Sonnenburg
00008  * Copyright (C) 1999-2008 Fraunhofer Institute FIRST and Max-Planck-Society
00009  */
00010 
00011 #include "lib/config.h"
00012 #include "lib/common.h"
00013 #include "lib/io.h"
00014 #include "lib/lapack.h"
00015 #include "kernel/SigmoidKernel.h"
00016 #include "features/Features.h"
00017 #include "features/RealFeatures.h"
00018 
00019 CSigmoidKernel::CSigmoidKernel(INT size, DREAL g, DREAL c)
00020 : CSimpleKernel<DREAL>(size),gamma(g), coef0(c)
00021 {
00022 }
00023 
00024 CSigmoidKernel::CSigmoidKernel(
00025     CRealFeatures* l, CRealFeatures* r, INT size, DREAL g, DREAL c)
00026 : CSimpleKernel<DREAL>(size),gamma(g), coef0(c)
00027 {
00028     init(l,r);
00029 }
00030 
00031 CSigmoidKernel::~CSigmoidKernel()
00032 {
00033     cleanup();
00034 }
00035 
00036 bool CSigmoidKernel::init(CFeatures* l, CFeatures* r)
00037 {
00038     CSimpleKernel<DREAL>::init(l, r);
00039     return true;
00040 }
00041 
00042 void CSigmoidKernel::cleanup()
00043 {
00044 }
00045 
00046 bool CSigmoidKernel::load_init(FILE* src)
00047 {
00048     return false;
00049 }
00050 
00051 bool CSigmoidKernel::save_init(FILE* dest)
00052 {
00053     return false;
00054 }
00055 
00056 DREAL CSigmoidKernel::compute(INT idx_a, INT idx_b)
00057 {
00058     INT alen, blen;
00059     bool afree, bfree;
00060 
00061     double* avec=((CRealFeatures*) lhs)->get_feature_vector(idx_a, alen, afree);
00062     double* bvec=((CRealFeatures*) rhs)->get_feature_vector(idx_b, blen, bfree);
00063     ASSERT(alen==blen);
00064 
00065 #ifndef HAVE_LAPACK
00066     DREAL result=0;
00067     {
00068         for (INT i=0; i<alen; i++)
00069             result+=avec[i]*bvec[i];
00070     }
00071 #else
00072     INT skip=1;
00073     DREAL result = cblas_ddot(alen, avec, skip, bvec, skip);
00074 #endif
00075 
00076     ((CRealFeatures*) lhs)->free_feature_vector(avec, idx_a, afree);
00077     ((CRealFeatures*) rhs)->free_feature_vector(bvec, idx_b, bfree);
00078 
00079     return tanh(gamma*result+coef0);
00080 }

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