PLearn 0.1
SumSquareVariable.cc
Go to the documentation of this file.
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: SumSquareVariable.cc 10210 2009-05-22 19:03:34Z plearner $
00040  * This file is part of the PLearn library.
00041  ******************************************************* */
00042 
00043 #include "SumSquareVariable.h"
00044 #include "Var_operators.h"
00045 //#include "Var_utils.h"
00046 
00047 namespace PLearn {
00048 using namespace std;
00049 
00050 
00053 PLEARN_IMPLEMENT_OBJECT(SumSquareVariable,
00054                         "Computes the sum of the squares of the values of all elements of its input",
00055                         "");
00056 
00057 SumSquareVariable::SumSquareVariable(Variable* input)
00058     : inherited(input, 1, 1) {}
00059 
00060 void SumSquareVariable::recomputeSize(int& l, int& w) const
00061 { l=1; w=1; }
00062 
00063 void SumSquareVariable::fprop()
00064 {
00065     int n=input->nelems();
00066     const real* inputdata = input->valuedata;
00067     real sumsq = 0;
00068     for(int i=0; i<n; i++)
00069     {
00070         real v = inputdata[i];
00071         sumsq += v*v;
00072     }
00073     *valuedata = sumsq;
00074 }
00075 
00076 
00077 void SumSquareVariable::bprop()
00078 {
00079     int n=input->nelems();
00080     for(int i=0; i<n; i++)
00081         input->gradientdata[i]+= 2.0 * input->valuedata[i] * *gradientdata;
00082 }
00083 
00084 
00085 void SumSquareVariable::symbolicBprop()
00086 {
00087     input->accg(2.0 * (g*input));
00088 }
00089 
00090 
00091 
00092 } // end of namespace PLearn
00093 
00094 
00095 /*
00096   Local Variables:
00097   mode:c++
00098   c-basic-offset:4
00099   c-file-style:"stroustrup"
00100   c-file-offsets:((innamespace . 0)(inline-open . 0))
00101   indent-tabs-mode:nil
00102   fill-column:79
00103   End:
00104 */
00105 // vim: filetype=cpp:expandtab:shiftwidth=4:tabstop=8:softtabstop=4:encoding=utf-8:textwidth=79 :
 All Classes Namespaces Files Functions Variables Typedefs Enumerations Enumerator Friends Defines