PLearn 0.1
HardSlopeVariable.h
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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: HardSlopeVariable.h 3994 2005-08-25 13:35:03Z chapados $
00040  * This file is part of the PLearn library.
00041  ******************************************************* */
00042 
00043 #ifndef HardSlopeVariable_INC
00044 #define HardSlopeVariable_INC
00045 
00046 #include "NaryVariable.h"
00047 #include "Var_operators.h"
00048 #include "Var_all.h"
00049 
00050 namespace PLearn {
00051 using namespace std;
00052 
00053 
00054 // linear by part function that
00055 // is 0 in [-infty,left], linear in [left,right], and 1 in [right,infty].
00056 class HardSlopeVariable: public NaryVariable
00057 {
00058     typedef NaryVariable inherited;
00059 
00060 public:
00062     HardSlopeVariable() {}
00063     HardSlopeVariable(Variable* x, Variable* left, Variable* right);
00064 
00065     PLEARN_DECLARE_OBJECT(HardSlopeVariable);
00066 
00067     virtual void recomputeSize(int& l, int& w) const;  
00068     virtual void fprop();
00069     virtual void bprop();
00070     virtual void symbolicBprop();
00071 };
00072 
00073 DECLARE_OBJECT_PTR(HardSlopeVariable);
00074 
00075 inline Var hard_slope(Var x, Var left, Var right)
00076 { return new HardSlopeVariable(x,left,right); }
00077 
00078 // derivative of hard_slope wrt x
00079 inline Var d_hard_slope(Var x, Var left, Var right)
00080 {
00081     return ifThenElse((x>=left)*(x<=right), invertElements(right-left), var(0.0));
00082 }
00083 
00084 } // end of namespace PLearn
00085 
00086 #endif 
00087 
00088 
00089 /*
00090   Local Variables:
00091   mode:c++
00092   c-basic-offset:4
00093   c-file-style:"stroustrup"
00094   c-file-offsets:((innamespace . 0)(inline-open . 0))
00095   indent-tabs-mode:nil
00096   fill-column:79
00097   End:
00098 */
00099 // vim: filetype=cpp:expandtab:shiftwidth=4:tabstop=8:softtabstop=4:encoding=utf-8:textwidth=79 :
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