PLearn 0.1
SumAbsVariable.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: SumAbsVariable.cc 6397 2006-11-08 05:49:18Z chapados $
00040  * This file is part of the PLearn library.
00041  ******************************************************* */
00042 
00043 #include "AbsVariable.h"
00044 #include "SumAbsVariable.h"
00045 #include "Var_operators.h"
00046 //#include "Var_utils.h"
00047 
00048 namespace PLearn {
00049 using namespace std;
00050 
00051 
00054 PLEARN_IMPLEMENT_OBJECT(
00055     SumAbsVariable,
00056     "Sum of the absolute value of the elements of its input",
00057     "This Variable always has a size of 1 element:\n"
00058     "\n"
00059     "   value(0,0) = sum_i abs(input[i])\n"
00060     "\n"
00061     "where input[i] is the i-th element of its input variable\n"
00062     "(dimensionality does not matter; it's viewed as a long vector).");
00063 
00064 SumAbsVariable::SumAbsVariable(Variable* input)
00065     : inherited(input, 1, 1) {}
00066 
00067 void SumAbsVariable::recomputeSize(int& l, int& w) const
00068 { l=1; w=1; }
00069 
00070 void SumAbsVariable::fprop()
00071 {
00072     int n=input->nelems();
00073     *valuedata= 0;
00074     for(int i=0; i<n; i++)
00075         *valuedata+= fabs(input->valuedata[i]);
00076 }
00077 
00078 
00079 void SumAbsVariable::bprop()
00080 {
00081     int n=input->nelems();
00082     for(int i=0; i<n; i++)
00083         if (input->valuedata[i]>0)
00084             input->gradientdata[i]+= *gradientdata;
00085         else if (input->valuedata[i]<0)
00086             input->gradientdata[i]-= *gradientdata;
00087 }
00088 
00089 
00090 void SumAbsVariable::symbolicBprop()
00091 {
00092     input->accg(g*abs(input));
00093 }
00094 
00095 
00096 
00097 } // end of namespace PLearn
00098 
00099 
00100 /*
00101   Local Variables:
00102   mode:c++
00103   c-basic-offset:4
00104   c-file-style:"stroustrup"
00105   c-file-offsets:((innamespace . 0)(inline-open . 0))
00106   indent-tabs-mode:nil
00107   fill-column:79
00108   End:
00109 */
00110 // vim: filetype=cpp:expandtab:shiftwidth=4:tabstop=8:softtabstop=4:encoding=utf-8:textwidth=79 :
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