PLearn 0.1
SoftplusVariable.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: SoftplusVariable.cc 8956 2008-05-08 19:19:03Z tihocan $
00040  * This file is part of the PLearn library.
00041  ******************************************************* */
00042 
00043 #include "SigmoidVariable.h"
00044 #include "SoftplusVariable.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         SoftplusVariable,
00056        "This is the primitive of a sigmoid: log(1+exp(x)).",
00057        ""
00058 );
00059 
00061 // SoftplusVariable //
00063 SoftplusVariable::SoftplusVariable(Variable* input, bool call_build_):
00064     inherited(input, input->length(), input->width(), call_build_)
00065 {
00066     if (call_build_)
00067         build_();
00068 }
00069 
00071 // build //
00073 void SoftplusVariable::build() {
00074     inherited::build();
00075     build_();
00076 }
00077 
00079 // build_ //
00081 void SoftplusVariable::build_() {
00082     // Nothing to do here.
00083 }
00084 
00086 // recomputeSize //
00088 void SoftplusVariable::recomputeSize(int& l, int& w) const
00089 {
00090     if (input) {
00091         l = input->length();
00092         w = input->width();
00093     } else
00094         l = w = 0;
00095 }
00096 
00097 void SoftplusVariable::fprop()
00098 {
00099     for(int i=0; i<nelems(); i++)
00100         valuedata[i] = softplus(input->valuedata[i]);
00101 }
00102 
00103 
00104 void SoftplusVariable::bprop()
00105 {
00106     for(int i=0; i<nelems(); i++)
00107         input->gradientdata[i] += gradientdata[i] * sigmoid(input->valuedata[i]);
00108 }
00109 
00110 
00111 void SoftplusVariable::symbolicBprop()
00112 {
00113     Var v(this);
00114     input->accg(g*sigmoid(input));
00115 }
00116 
00117 
00118 
00119 } // end of namespace PLearn
00120 
00121 
00122 /*
00123   Local Variables:
00124   mode:c++
00125   c-basic-offset:4
00126   c-file-style:"stroustrup"
00127   c-file-offsets:((innamespace . 0)(inline-open . 0))
00128   indent-tabs-mode:nil
00129   fill-column:79
00130   End:
00131 */
00132 // 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