PLearn 0.1
IdentityVariable.cc
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00001 // -*- C++ -*-
00002 
00003 // PLearn (A C++ Machine Learning Library)
00004 // Copyright (C) 2004 Jasmin Lapalme
00005 
00006 // Redistribution and use in source and binary forms, with or without
00007 // modification, are permitted provided that the following conditions are met:
00008 // 
00009 //  1. Redistributions of source code must retain the above copyright
00010 //     notice, this list of conditions and the following disclaimer.
00011 // 
00012 //  2. Redistributions in binary form must reproduce the above copyright
00013 //     notice, this list of conditions and the following disclaimer in the
00014 //     documentation and/or other materials provided with the distribution.
00015 // 
00016 //  3. The name of the authors may not be used to endorse or promote
00017 //     products derived from this software without specific prior written
00018 //     permission.
00019 // 
00020 // THIS SOFTWARE IS PROVIDED BY THE AUTHORS ``AS IS'' AND ANY EXPRESS OR
00021 // IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
00022 // OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN
00023 // NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
00024 // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
00025 // TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
00026 // PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
00027 // LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
00028 // NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
00029 // SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
00030 // 
00031 // This file is part of the PLearn library. For more information on the PLearn
00032 // library, go to the PLearn Web site at www.plearn.org
00033 
00034 #include "IdentityVariable.h"
00035 #include "Var_operators.h"
00036 
00037 namespace PLearn {
00038 using namespace std;
00039 
00040 
00043 PLEARN_IMPLEMENT_OBJECT(IdentityVariable,
00044                         "Variable that computes f(x)=x and f'(x)=1.0",
00045                         "NO HELP");
00046 
00047 IdentityVariable::IdentityVariable(Variable* input) 
00048     : inherited(input, input->length(), input->width())
00049 {}
00050 
00051 void IdentityVariable::recomputeSize(int& l, int& w) const {
00052     if (input) {
00053         l = input->length();
00054         w = input->width();
00055     } else
00056         l = w = 0;
00057 }
00058 
00059 void IdentityVariable::fprop() {
00060     int l = nelems();
00061     real* inputptr = input->valuedata;
00062     real* ptr = valuedata;
00063     for(int i=0; i<l; i++)
00064         *ptr++ = *inputptr++;
00065 }
00066 
00067 
00068 void IdentityVariable::bprop() {
00069     int l = nelems();
00070     real* inputgradientptr = input->gradientdata;
00071     real* gradientptr = gradientdata;
00072 
00073     for(int i=0; i<l; i++)
00074         *inputgradientptr++ += *gradientptr++ * 1.0;
00075 }
00076 
00077 void IdentityVariable::bbprop() {
00078     PLERROR("bbprop is not implemented for IdentityVariable");
00079 }
00080 
00081 
00082 void IdentityVariable::symbolicBprop() {
00083     PLERROR("symbolicBprop is not implemented for IdentityVariable");
00084 }
00085 
00086 void IdentityVariable::rfprop() {
00087     PLERROR("rfprop is not implemented for IdentityVariable");
00088 }
00089 
00090 } // end of namespace PLearn
00091 
00092 
00093 /*
00094   Local Variables:
00095   mode:c++
00096   c-basic-offset:4
00097   c-file-style:"stroustrup"
00098   c-file-offsets:((innamespace . 0)(inline-open . 0))
00099   indent-tabs-mode:nil
00100   fill-column:79
00101   End:
00102 */
00103 // vim: filetype=cpp:expandtab:shiftwidth=4:tabstop=8:softtabstop=4:encoding=utf-8:textwidth=79 :
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