library: libGraf #include "TGraphErrors.h"

# TGraphErrors

class description - source file - inheritance tree (.pdf)

## class TGraphErrors : public TGraph

| Inheritance Chart:

`TObject`

<-

`TNamed`

`TAttLine`

`TAttFill`

`TAttMarker`

<-

`TGraph`

<-

`TGraphErrors`

        protected:

          virtual Double_t** Allocate(Int_t size)
                virtual void CopyAndRelease(Double_t** newarrays, Int_t ibegin, Int_t iend, Int_t obegin)
              virtual Bool_t CopyPoints(Double_t** arrays, Int_t ibegin, Int_t iend, Int_t obegin)
                      Bool_t CtorAllocate()
                virtual void FillZero(Int_t begin, Int_t end, Bool_t from_ctor = kTRUE)
                virtual void SwapPoints(Int_t pos1, Int_t pos2)

        public:

                            TGraphErrors()
                            TGraphErrors(Int_t n)
                            TGraphErrors(Int_t n, const Float_t* x, const Float_t* y, const Float_t* ex = 0, const Float_t* ey = 0)
                            TGraphErrors(Int_t n, const Double_t* x, const Double_t* y, const Double_t* ex = 0, const Double_t* ey = 0)
                            TGraphErrors(const TVector& vx, const TVector& vy, const TVector& vex, const TVector& vey)
                            TGraphErrors(const TVectorD& vx, const TVectorD& vy, const TVectorD& vex, const TVectorD& vey)
                            TGraphErrors(const TGraphErrors& gr)
                            TGraphErrors(const TH1* h)
                            TGraphErrors(const char* filename, const char* format = "%lg %lg %lg %lg", Option_t* option = "")
                    virtual ~TGraphErrors()
               virtual void Apply(TF1* f)
               static Int_t CalculateScanfFields(const char* fmt)
             static TClass* Class()
               virtual void ComputeRange(Double_t& xmin, Double_t& ymin, Double_t& xmax, Double_t& ymax) const
           virtual Double_t GetErrorX(Int_t bin) const
           virtual Double_t GetErrorXhigh(Int_t bin) const
           virtual Double_t GetErrorXlow(Int_t bin) const
           virtual Double_t GetErrorY(Int_t bin) const
           virtual Double_t GetErrorYhigh(Int_t bin) const
           virtual Double_t GetErrorYlow(Int_t bin) const
          virtual Double_t* GetEX() const
          virtual Double_t* GetEY() const
            virtual TClass* IsA() const
              TGraphErrors& operator=(const TGraphErrors&)
               virtual void Paint(Option_t* chopt = "")
               virtual void Print(Option_t* chopt = "") const
               virtual void SavePrimitive(ofstream& out, Option_t* option)
               virtual void SetPointError(Double_t ex, Double_t ey)
               virtual void SetPointError(Int_t i, Double_t ex, Double_t ey)
               virtual void ShowMembers(TMemberInspector& insp, char* parent)
               virtual void Streamer(TBuffer& b)
                       void StreamerNVirtual(TBuffer& b)

### Data Members

        protected:

          Double_t* fEX  [fNpoints] array of X errors
          Double_t* fEY  [fNpoints] array of Y errors

## Class Description

       A TGraphErrors is a TGraph with error bars.
       The various format options to draw a TGraphErrors are explained in
         TGraphErrors::Paint.

      The picture below has been generated by the following macro:
    ------------------------------------------------------------------------
    {
       gROOT->Reset();
       c1 = new TCanvas("c1","A Simple Graph with error bars",200,10,700,500);

       c1->SetFillColor(42);
       c1->SetGrid();
       c1->GetFrame()->SetFillColor(21);
       c1->GetFrame()->SetBorderSize(12);

       Int_t n = 10;
       Double_t x[n]  = {-0.22, 0.05, 0.25, 0.35, 0.5, 0.61,0.7,0.85,0.89,0.95};
       Double_t y[n]  = {1,2.9,5.6,7.4,9,9.6,8.7,6.3,4.5,1};
       Double_t ex[n] = {.05,.1,.07,.07,.04,.05,.06,.07,.08,.05};
       Double_t ey[n] = {.8,.7,.6,.5,.4,.4,.5,.6,.7,.8};
       gr = new TGraphErrors(n,x,y,ex,ey);
       gr->SetTitle("TGraphErrors Example");
       gr->SetMarkerColor(4);
       gr->SetMarkerStyle(21);
       gr->Draw("ALP");

       c1->Update();
    }

/* */

TGraphErrors(): TGraph()

    *-*-*-*-*-*-*-*-*-*-*TGraphErrors default constructor*-*-*-*-*-*-*-*-*-*-*-*
    *-*                  ================================

TGraphErrors(Int_t n) : TGraph(n)

    *-*-*-*-*-*-*-*-*-*-*TGraphErrors normal constructor*-*-*-*-*-*-*-*-*-*-*-*-*
    *-*                  ===============================

      the arrays are preset to zero

TGraphErrors(Int_t n, const Float_t *x, const Float_t *y, const Float_t *ex, const Float_t *ey) : TGraph(n,x,y)

    *-*-*-*-*-*-*-*-*-*-*TGraphErrors normal constructor*-*-*-*-*-*-*-*-*-*-*-*-*
    *-*                  ===============================

      if ex or ey are null, the corresponding arrays are preset to zero

TGraphErrors(Int_t n, const Double_t *x, const Double_t *y, const Double_t *ex, const Double_t *ey) : TGraph(n,x,y)

    *-*-*-*-*-*-*-*-*-*-*TGraphErrors normal constructor*-*-*-*-*-*-*-*-*-*-*-*-*
    *-*                  ===============================

      if ex or ey are null, the corresponding arrays are preset to zero

TGraphErrors(const TVector &vx, const TVector &vy, const TVector &vex, const TVector &vey) :TGraph()

     constructor with four vectors of floats in input
     A grapherrors is built with the X coordinates taken from vx and Y coord from vy
     and the errors from vectors vex and vey.
     The number of points in the graph is the minimum of number of points
     in vx and vy.

TGraphErrors(const TVectorD &vx, const TVectorD &vy, const TVectorD &vex, const TVectorD &vey) :TGraph()

     constructor with four vectors of doubles in input
     A grapherrors is built with the X coordinates taken from vx and Y coord from vy
     and the errors from vectors vex and vey.
     The number of points in the graph is the minimum of number of points
     in vx and vy.

TGraphErrors(const TGraphErrors &gr) : TGraph(gr)

     TGraphErrors copy constructor

TGraphErrors(const TH1 *h) : TGraph(h)

     TGraphErrors constructor importing its parameters from the TH1 object passed as argument

TGraphErrors(const char *filename, const char *format, Option_t *) : TGraph(100)

     GraphErrors constructor reading input from filename
     filename is assumed to contain at least 3 columns of numbers
     convention for format (default="%lg %lg %lg %lg)
      format = "%lg %lg"         read only 2 first columns into X,Y
      format = "%lg %lg %lg"     read only 3 first columns into X,Y and EY
      format = "%lg %lg %lg %lg" read only 4 first columns into X,Y,EX,EY

~TGraphErrors()

    *-*-*-*-*-*-*-*-*-*-*TGraphErrors default destructor*-*-*-*-*-*-*-*-*-*-*-*-*
    *-*                  ===============================

void Apply(TF1 *f)

     apply function to all the data points
     y = f(x,y)

     The error is calculated as ey=(f(x,y+ey)-f(x,y-ey))/2
     This is the same as error(fy) = df/dy * ey for small errors

     For generic functions the symmetric errors might become non-symmetric
     and are averaged here. Use TGraphAsymmErrors if desired.

     error on x doesn't change
     function suggested/implemented by Miroslav Helbich <helbich@mail.desy.de>

Int_t CalculateScanfFields(const char *fmt)

void ComputeRange(Double_t &xmin, Double_t &ymin, Double_t &xmax, Double_t &ymax) const

void CopyAndRelease(Double_t **newarrays, Int_t ibegin, Int_t iend, Int_t obegin)

Bool_t CopyPoints(Double_t **arrays, Int_t ibegin, Int_t iend, Int_t obegin)

     Copy errors from fEX and fEY to arrays[0] and arrays[1]
     or to fX and fY. Copy points.

Bool_t CtorAllocate()

void FillZero(Int_t begin, Int_t end, Bool_t from_ctor)

     Set zero values for point arrays in the range [begin, end)

Double_t GetErrorX(Int_t i) const

        This function is called by GraphFitChisquare.
        It returns the error along X at point i.

Double_t GetErrorY(Int_t i) const

        This function is called by GraphFitChisquare.
        It returns the error along Y at point i.

Double_t GetErrorXhigh(Int_t i) const

        This function is called by GraphFitChisquare.
        It returns the error along X at point i.

Double_t GetErrorXlow(Int_t i) const

        This function is called by GraphFitChisquare.
        It returns the error along X at point i.

Double_t GetErrorYhigh(Int_t i) const

        This function is called by GraphFitChisquare.
        It returns the error along X at point i.

Double_t GetErrorYlow(Int_t i) const

        This function is called by GraphFitChisquare.
        It returns the error along X at point i.

void Paint(Option_t *option)

     Paint this TGraphErrors with its current attributes

     by default horizonthal and vertical small lines are drawn at
     the end of the error bars. if option "z" or "Z" is specified,
     these lines are not drawn.

     if option contains ">" an arrow is drawn at the end of the error bars
     if option contains "|>" a full arrow is drawn at the end of the error bars
     the size of the arrow is set to 2/3 of the marker size.

     By default, error bars are drawn. If option "X" is specified,
     the errors are not drawn (TGraph::Paint equivalent).

     if option "[]" is specified only the end vertical/horizonthal lines
     of the error bars are drawn. This option is interesting to superimpose
     systematic errors on top of a graph with statistical errors.

     if option "2" is specified error rectangles are drawn.

     if option "3" is specified a filled area is drawn through the end points of
     the vertical error bars.

     if option "4" is specified a smoothed filled area is drawn through the end
     points of the vertical error bars.

     Use gStyle->SetErrorX(dx) to control the size of the error along x.
     set dx = 0 to suppress the error along x.

     Use gStyle->SetEndErrorSize(np) to control the size of the lines
     at the end of the error bars (when option 1 is used).
     By default np=1. (np represents the number of pixels).

void Print(Option_t *) const

    *-*-*-*-*-*-*-*-*-*-*Print graph and errors values*-*-*-*-*-*-*-*-*-*-*-*
    *-*                  =============================

void SavePrimitive(ofstream &out, Option_t *option)

     Save primitive as a C++ statement(s) on output stream out

void SetPointError(Double_t ex, Double_t ey)

    *-*-*-*-*-*-*Set ex and ey values for point pointed by the mouse*-*-*-*
    *-*          ===================================================

void SetPointError(Int_t i, Double_t ex, Double_t ey)

    *-*-*-*-*-*-*-*-*-*-*Set ex and ey values for point number i*-*-*-*-*-*-*-*
    *-*                  =======================================

void Streamer(TBuffer &b)

     Stream an object of class TGraphErrors.

void SwapPoints(Int_t pos1, Int_t pos2)

### Inline Functions

               Double_t** Allocate(Int_t size)
                Double_t* GetEX() const
                Double_t* GetEY() const
                  TClass* Class()
                  TClass* IsA() const
                     void ShowMembers(TMemberInspector& insp, char* parent)
                     void StreamerNVirtual(TBuffer& b)
            TGraphErrors& operator=(const TGraphErrors&)

Author: Rene Brun 15/09/96
Last update: root/graf:$Name: $:$Id: TGraphErrors.cxx,v 1.49 2005/06/13 10:10:29 brun Exp $
Copyright (C) 1995-2000, Rene Brun and Fons Rademakers. *