PLearn 0.1
LogOfGaussianDensityKernel.cc
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00001 // -*- C++ -*-
00002 
00003 // PLearn (A C++ Machine Learning Library)
00004 // Copyright (C) 1998 Pascal Vincent
00005 // Copyright (C) 1999-2002 Pascal Vincent, Yoshua Bengio, Rejean Ducharme and University of Montreal
00006 // Copyright (C) 2001-2002 Nicolas Chapados, Ichiro Takeuchi, Jean-Sebastien Senecal
00007 // Copyright (C) 2002 Xiangdong Wang, Christian Dorion
00008 
00009 // Redistribution and use in source and binary forms, with or without
00010 // modification, are permitted provided that the following conditions are met:
00011 // 
00012 //  1. Redistributions of source code must retain the above copyright
00013 //     notice, this list of conditions and the following disclaimer.
00014 // 
00015 //  2. Redistributions in binary form must reproduce the above copyright
00016 //     notice, this list of conditions and the following disclaimer in the
00017 //     documentation and/or other materials provided with the distribution.
00018 // 
00019 //  3. The name of the authors may not be used to endorse or promote
00020 //     products derived from this software without specific prior written
00021 //     permission.
00022 // 
00023 // THIS SOFTWARE IS PROVIDED BY THE AUTHORS ``AS IS'' AND ANY EXPRESS OR
00024 // IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
00025 // OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN
00026 // NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
00027 // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
00028 // TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
00029 // PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
00030 // LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
00031 // NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
00032 // SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
00033 // 
00034 // This file is part of the PLearn library. For more information on the PLearn
00035 // library, go to the PLearn Web site at www.plearn.org
00036 
00037 
00038 /* *******************************************************      
00039  * $Id: LogOfGaussianDensityKernel.cc 3994 2005-08-25 13:35:03Z chapados $
00040  * This file is part of the PLearn library.
00041  ******************************************************* */
00042 
00043 #include "LogOfGaussianDensityKernel.h"
00044 
00045 namespace PLearn {
00046 using namespace std;
00047 
00048 
00049 PLEARN_IMPLEMENT_OBJECT(LogOfGaussianDensityKernel, "ONE LINE DESCR", "NO HELP");
00050 
00051 real LogOfGaussianDensityKernel::evaluate(const Vec& x1, const Vec& x2) const
00052 { 
00053     // cerr << "LogOfGaussKernel mu: " << x1 << endl; 
00054     double sigmasq = sigma*sigma;
00055     // cerr << "sqnorm_xmu " << powdistance(x1, x2, real(2.0)) << endl;
00056     // cerr << "sigmasq " << sigmasq << endl;
00057     double q = powdistance(x1, x2, real(2.0))/sigmasq;
00058     // cerr << "log of gauss kernel q = " << q << endl; 
00059     //double logp = -0.5 * ( q + x1.length()*( log(2*M_PI) + log(sigmasq)) ); 
00060     double logp = -0.5 * ( q + x1.length()*( log(2*Pi) + log(sigmasq)) ); 
00061     // cerr << "logp = " << logp << endl;
00062     // exit(0);
00063     return real(logp);
00064 }
00065 
00066 
00067 void LogOfGaussianDensityKernel::declareOptions(OptionList& ol)
00068 {
00069     declareOption(ol, "sigma", &LogOfGaussianDensityKernel::sigma, OptionBase::buildoption,
00070                   "The width of the Gaussian");
00071     inherited::declareOptions(ol);
00072 }
00073 
00074 
00075 
00076 } // end of namespace PLearn
00077 
00078 
00079 /*
00080   Local Variables:
00081   mode:c++
00082   c-basic-offset:4
00083   c-file-style:"stroustrup"
00084   c-file-offsets:((innamespace . 0)(inline-open . 0))
00085   indent-tabs-mode:nil
00086   fill-column:79
00087   End:
00088 */
00089 // vim: filetype=cpp:expandtab:shiftwidth=4:tabstop=8:softtabstop=4:encoding=utf-8:textwidth=79 :
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