PLearn 0.1
SumVariable.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: SumVariable.cc 6397 2006-11-08 05:49:18Z chapados $
00040  * This file is part of the PLearn library.
00041  ******************************************************* */
00042 
00043 #include "SumVariable.h"
00044 
00045 namespace PLearn {
00046 using namespace std;
00047 
00048 
00049 
00052 PLEARN_IMPLEMENT_OBJECT(
00053     SumVariable,
00054     "Compute the sum of all elements in the input Var",
00055     "This Variable always has a size of 1 element:\n"
00056     "\n"
00057     "   value(0,0) = sum_i input[i]\n"
00058     "\n"
00059     "where input[i] is the i-th element of its input variable\n"
00060     "(dimensionality does not matter; it's viewed as a long vector).");
00061 
00062 SumVariable::SumVariable(Variable* input)
00063     : inherited(input, 1, 1)
00064 {}
00065 
00066 void SumVariable::recomputeSize(int& l, int& w) const
00067 { l=1; w=1; }
00068 
00069 void SumVariable::fprop()
00070 {
00071     real sum = 0.0;
00072     for(int k=0; k<input->nelems(); k++)
00073         sum += input->valuedata[k];
00074     valuedata[0] = sum;
00075 }
00076 
00077 
00078 void SumVariable::bprop()
00079 {
00080     real grd = gradientdata[0];
00081     for(int k=0; k<input->nelems(); k++)
00082         input->gradientdata[k] += grd;
00083 }
00084 
00085 
00086 void SumVariable::symbolicBprop()
00087 {
00088     input->accg(g);
00089 }
00090 
00091 
00092 // R(sum_i x_i) = sum_i R(x_i)
00093 void SumVariable::rfprop()
00094 {
00095     if (rValue.length()==0) resizeRValue();
00096     real sum = 0.0;
00097     for(int k=0; k<input->nelems(); k++)
00098         sum += input->rvaluedata[k];
00099     rvaluedata[0] = sum;
00100 }
00101 
00102 
00103 
00104 } // end of namespace PLearn
00105 
00106 
00107 /*
00108   Local Variables:
00109   mode:c++
00110   c-basic-offset:4
00111   c-file-style:"stroustrup"
00112   c-file-offsets:((innamespace . 0)(inline-open . 0))
00113   indent-tabs-mode:nil
00114   fill-column:79
00115   End:
00116 */
00117 // vim: filetype=cpp:expandtab:shiftwidth=4:tabstop=8:softtabstop=4:encoding=utf-8:textwidth=79 :
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