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TNeuron.h
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1 // @(#)root/mlp:$Id$
2 // Author: Christophe.Delaere@cern.ch 20/07/03
3 
4 /*************************************************************************
5  * Copyright (C) 1995-2003, Rene Brun and Fons Rademakers. *
6  * All rights reserved. *
7  * *
8  * For the licensing terms see $ROOTSYS/LICENSE. *
9  * For the list of contributors see $ROOTSYS/README/CREDITS. *
10  *************************************************************************/
11 
12 #ifndef ROOT_TNeuron
13 #define ROOT_TNeuron
14 
15 #include "TNamed.h"
16 #include "TObjArray.h"
17 
18 class TTreeFormula;
19 class TSynapse;
20 class TBranch;
21 class TTree;
22 class TFormula;
23 
24 //____________________________________________________________________
25 //
26 // TNeuron
27 //
28 // This class decribes an elementary neuron, which is the basic
29 // element for a Neural Network.
30 // A network is build connecting neurons by synapses.
31 // There are different types of neurons: linear (a+bx),
32 // sigmoid (1/(1+exp(-x)), tanh or gaussian.
33 // In a Multi Layer Perceptron, the input layer is made of
34 // inactive neurons (returning the normalized input), hidden layers
35 // are made of sigmoids and output neurons are linear.
36 //
37 // This implementation contains several methods to compute the value,
38 // the derivative, the DeDw, ...
39 // Values are stored in local buffers. The SetNewEvent() method is
40 // there to inform buffered values are outdated.
41 //
42 //____________________________________________________________________
43 
44 class TNeuron : public TNamed {
45  friend class TSynapse;
46 
47  public:
49 
51  const char* name = "", const char* title = "",
52  const char* extF = "", const char* extD = "" );
53  virtual ~TNeuron() {}
54  inline TSynapse* GetPre(Int_t n) const { return (TSynapse*) fpre.At(n); }
55  inline TSynapse* GetPost(Int_t n) const { return (TSynapse*) fpost.At(n); }
56  inline TNeuron* GetInLayer(Int_t n) const { return (TNeuron*) flayer.At(n); }
57  TTreeFormula* UseBranch(TTree*, const char*);
58  Double_t GetInput() const;
59  Double_t GetValue() const;
60  Double_t GetDerivative() const;
61  Double_t GetError() const;
62  Double_t GetTarget() const;
63  Double_t GetDeDw() const;
64  Double_t GetBranch() const;
65  ENeuronType GetType() const;
66  void SetWeight(Double_t w);
67  inline Double_t GetWeight() const { return fWeight; }
69  inline const Double_t* GetNormalisation() const { return fNorm; }
70  void SetNewEvent() const;
71  void SetDEDw(Double_t in);
72  inline Double_t GetDEDw() const { return fDEDw; }
73  void ForceExternalValue(Double_t value);
74  void AddInLayer(TNeuron*);
75 
76  protected:
77  Double_t Sigmoid(Double_t x) const;
78  Double_t DSigmoid(Double_t x) const;
79  void AddPre(TSynapse*);
80  void AddPost(TSynapse*);
81 
82  private:
83  TNeuron(const TNeuron&); // Not implemented
84  TNeuron& operator=(const TNeuron&); // Not implemented
85 
86  TObjArray fpre; // pointers to the previous level in a network
87  TObjArray fpost; // pointers to the next level in a network
88  TObjArray flayer; // pointers to the current level in a network (neurons, not synapses)
89  Double_t fWeight; // weight used for computation
90  Double_t fNorm[2]; // normalisation to mean=0, RMS=1.
91  ENeuronType fType; // neuron type
92  TFormula* fExtF; // function (external mode)
93  TFormula* fExtD; // derivative (external mode)
94  //buffers
95  //should be mutable when supported by all compilers
96  TTreeFormula* fFormula;//! formula to be used for inputs and outputs
97  Int_t fIndex; //! index in the formula
98  Bool_t fNewInput; //! do we need to compute fInput again ?
99  Double_t fInput; //! buffer containing the last neuron input
100  Bool_t fNewValue; //! do we need to compute fValue again ?
101  Double_t fValue; //! buffer containing the last neuron output
102  Bool_t fNewDeriv; //! do we need to compute fDerivative again ?
103  Double_t fDerivative; //! buffer containing the last neuron derivative
104  Bool_t fNewDeDw; //! do we need to compute fDeDw again ?
105  Double_t fDeDw; //! buffer containing the last derivative of the error
106  Double_t fDEDw; //! buffer containing the sum over all examples of DeDw
107 
108  ClassDef(TNeuron, 4) // Neuron for MultiLayerPerceptrons
109 };
110 
111 #endif
ENeuronType GetType() const
Returns the neuron type.
Definition: TNeuron.cxx:867
TSynapse * GetPre(Int_t n) const
Definition: TNeuron.h:54
An array of TObjects.
Definition: TObjArray.h:37
void ForceExternalValue(Double_t value)
Uses the branch type to force an external value.
Definition: TNeuron.cxx:1125
TSynapse * GetPost(Int_t n) const
Definition: TNeuron.h:55
void SetNewEvent() const
Inform the neuron that inputs of the network have changed, so that the buffered values have to be rec...
Definition: TNeuron.cxx:1157
TObjArray flayer
Definition: TNeuron.h:88
ENeuronType
Definition: TNeuron.h:48
Bool_t fNewDeDw
buffer containing the last neuron derivative
Definition: TNeuron.h:104
int Int_t
Definition: RtypesCore.h:41
bool Bool_t
Definition: RtypesCore.h:59
TObject * At(Int_t idx) const
Definition: TObjArray.h:165
TFormula * fExtD
Definition: TNeuron.h:93
void AddPre(TSynapse *)
Adds a synapse to the neuron as an input This method is used by the TSynapse while connecting two neu...
Definition: TNeuron.cxx:834
Double_t GetBranch() const
Returns the formula value.
Definition: TNeuron.cxx:914
Double_t RMS(Long64_t n, const T *a, const Double_t *w=0)
Return the Standard Deviation of an array a with length n.
Definition: TMath.h:1192
Double_t x[n]
Definition: legend1.C:17
#define ClassDef(name, id)
Definition: Rtypes.h:320
Double_t fDerivative
do we need to compute fDerivative again ?
Definition: TNeuron.h:103
The TNamed class is the base class for all named ROOT classes.
Definition: TNamed.h:29
Double_t GetValue() const
Computes the output using the appropriate function and all the weighted inputs, or uses the branch as...
Definition: TNeuron.cxx:948
TTreeFormula * UseBranch(TTree *, const char *)
Sets a formula that can be used to make the neuron an input.
Definition: TNeuron.cxx:878
TObjArray fpost
Definition: TNeuron.h:87
TNeuron * GetInLayer(Int_t n) const
Definition: TNeuron.h:56
Double_t fWeight
Definition: TNeuron.h:89
Bool_t fNewDeriv
buffer containing the last neuron output
Definition: TNeuron.h:102
void SetWeight(Double_t w)
Sets the neuron weight to w.
Definition: TNeuron.cxx:1148
Used to pass a selection expression to the Tree drawing routine.
Definition: TTreeFormula.h:58
const Double_t * GetNormalisation() const
Definition: TNeuron.h:69
Double_t fDEDw
buffer containing the last derivative of the error
Definition: TNeuron.h:106
Double_t fValue
do we need to compute fValue again ?
Definition: TNeuron.h:101
Double_t fInput
do we need to compute fInput again ?
Definition: TNeuron.h:99
void AddInLayer(TNeuron *)
Tells a neuron which neurons form its layer (including itself).
Definition: TNeuron.cxx:857
void SetNormalisation(Double_t mean, Double_t RMS)
Sets the normalization variables.
Definition: TNeuron.cxx:1137
TNeuron & operator=(const TNeuron &)
The Formula class.
Definition: TFormula.h:83
TTreeFormula * fFormula
Definition: TNeuron.h:96
Double_t GetError() const
Computes the error for output neurons.
Definition: TNeuron.cxx:1063
void SetDEDw(Double_t in)
Sets the derivative of the total error wrt the neuron weight.
Definition: TNeuron.cxx:1168
TNeuron(ENeuronType type=kSigmoid, const char *name="", const char *title="", const char *extF="", const char *extD="")
Usual constructor.
Definition: TNeuron.cxx:51
Double_t Sigmoid(Double_t x) const
The Sigmoid.
Definition: TNeuron.cxx:95
Bool_t fNewValue
buffer containing the last neuron input
Definition: TNeuron.h:100
double Double_t
Definition: RtypesCore.h:55
Double_t GetDeDw() const
Computes the derivative of the error wrt the neuron weight.
Definition: TNeuron.cxx:1084
ENeuronType fType
Definition: TNeuron.h:91
Double_t GetDerivative() const
computes the derivative for the appropriate function at the working point
Definition: TNeuron.cxx:1011
int type
Definition: TGX11.cxx:120
Double_t GetTarget() const
Computes the normalized target pattern for output neurons.
Definition: TNeuron.cxx:1074
Int_t fIndex
formula to be used for inputs and outputs
Definition: TNeuron.h:97
TObjArray fpre
Definition: TNeuron.h:86
Double_t GetWeight() const
Definition: TNeuron.h:67
Bool_t fNewInput
index in the formula
Definition: TNeuron.h:98
Double_t fDeDw
do we need to compute fDeDw again ?
Definition: TNeuron.h:105
Double_t GetDEDw() const
Definition: TNeuron.h:72
TFormula * fExtF
Definition: TNeuron.h:92
void AddPost(TSynapse *)
Adds a synapse to the neuron as an output This method is used by the TSynapse while connecting two ne...
Definition: TNeuron.cxx:846
A TTree object has a header with a name and a title.
Definition: TTree.h:70
Double_t fNorm[2]
Definition: TNeuron.h:90
A TTree is a list of TBranches.
Definition: TBranch.h:62
virtual ~TNeuron()
Definition: TNeuron.h:53
Double_t GetInput() const
Returns neuron input.
Definition: TNeuron.cxx:925
const Int_t n
Definition: legend1.C:16
char name[80]
Definition: TGX11.cxx:109
Double_t DSigmoid(Double_t x) const
The Derivative of the Sigmoid.
Definition: TNeuron.cxx:818