PLearn 0.1
GaussianDensityKernel.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: GaussianDensityKernel.cc 9055 2008-05-26 14:13:18Z tihocan $
00040  * This file is part of the PLearn library.
00041  ******************************************************* */
00042 
00043 #include "GaussianDensityKernel.h"
00044 
00045 namespace PLearn {
00046 using namespace std;
00047 
00048 
00049 PLEARN_IMPLEMENT_OBJECT(GaussianDensityKernel, 
00050                         "The normal density with variance sigma^2: K(x,y) = 1/Z exp(-1/2 ||x-y||^2 / sigma^2) with Z = (2Pi)^(d/2) sigma^d", 
00051                         "");
00052 
00053 real GaussianDensityKernel::evaluate(const Vec& x1, const Vec& x2) const
00054 { return exp(-real(0.5)*powdistance(x1, x2, real(2.0))/(sigma*sigma) - x1.length()*(0.5*Log2Pi + pl_log(sigma))); }
00055 
00056 void GaussianDensityKernel::declareOptions(OptionList& ol)
00057 {
00058     declareOption(ol, "sigma", &GaussianDensityKernel::sigma, OptionBase::buildoption,
00059                   "The width of the Gaussian");
00060     inherited::declareOptions(ol);
00061 }
00062 
00063 } // end of namespace PLearn
00064 
00065 
00066 /*
00067   Local Variables:
00068   mode:c++
00069   c-basic-offset:4
00070   c-file-style:"stroustrup"
00071   c-file-offsets:((innamespace . 0)(inline-open . 0))
00072   indent-tabs-mode:nil
00073   fill-column:79
00074   End:
00075 */
00076 // vim: filetype=cpp:expandtab:shiftwidth=4:tabstop=8:softtabstop=4:encoding=utf-8:textwidth=79 :
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