// @(#)root/hist:$Name:  $:$Id: TProfile2D.cxx,v 1.24 2004/05/26 11:32:00 brun Exp $
// Author: Rene Brun   16/04/2000

/*************************************************************************
 * Copyright (C) 1995-2000, Rene Brun and Fons Rademakers.               *
 * All rights reserved.                                                  *
 *                                                                       *
 * For the licensing terms see $ROOTSYS/LICENSE.                         *
 * For the list of contributors see $ROOTSYS/README/CREDITS.             *
 *************************************************************************/

#include "TProfile2D.h"
#include "TMath.h"
#include "THLimitsFinder.h"
#include "Riostream.h"

Bool_t TProfile2D::fgApproximate = kFALSE;

ClassImp(TProfile2D)

//______________________________________________________________________________
//
//  Profile2D histograms are used to display the mean
//  value of Z and its RMS for each cell in X,Y.
//  Profile2D histograms are in many cases an
//  elegant replacement of three-dimensional histograms : the inter-relation of three
//  measured quantities X, Y and Z can always be visualized by a three-dimensional
//  histogram or scatter-plot; its representation on the line-printer is not particularly
//  satisfactory, except for sparse data. If Z is an unknown (but single-valued)
//  approximate function of X,Y this function is displayed by a profile2D histogram with
//  much better precision than by a scatter-plot.
//
//  The following formulae show the cumulated contents (capital letters) and the values
//  displayed by the printing or plotting routines (small letters) of the elements for cell I, J.
//
//                                                        2
//      H(I,J)  =  sum Z                  E(I,J)  =  sum Z
//      l(I,J)  =  sum l                  L(I,J)  =  sum l
//      h(I,J)  =  H(I,J)/L(I,J)          s(I,J)  =  sqrt(E(I,J)/L(I,J)- h(I,J)**2)
//      e(I,J)  =  s(I,J)/sqrt(L(I,J))
//
//  In the special case where s(I,J) is zero (eg, case of 1 entry only in one cell)
//  e(I,J) is computed from the average of the s(I,J) for all cells.
//  This simple/crude approximation was suggested in order to keep the cell
//  during a fit operation.
//
//           Example of a profile2D histogram
//{
//  TCanvas *c1 = new TCanvas("c1","Profile histogram example",200,10,700,500);
//  hprof2d  = new TProfile2D("hprof2d","Profile of pz versus px and py",40,-4,4,40,-4,4,0,20);
//  Float_t px, py, pz;
//  for ( Int_t i=0; i<25000; i++) {
//     gRandom->Rannor(px,py);
//     pz = px*px + py*py;
//     hprof2d->Fill(px,py,pz,1);
//  }
//  hprof2d->Draw();
//}
//

//______________________________________________________________________________
TProfile2D::TProfile2D() : TH2D()
{
//*-*-*-*-*-*Default constructor for Profile2D histograms*-*-*-*-*-*-*-*-*
//*-*        ============================================
   fTsumwz = fTsumwz2 = 0;
}

//______________________________________________________________________________
TProfile2D::~TProfile2D()
{
//*-*-*-*-*-*Default destructor for Profile2D histograms*-*-*-*-*-*-*-*-*
//*-*        ===========================================

}

//______________________________________________________________________________
TProfile2D::TProfile2D(const char *name,const char *title,Int_t nx,Axis_t xlow,Axis_t xup,Int_t ny,Axis_t ylow,Axis_t yup,Option_t *option)
    : TH2D(name,title,nx,xlow,xup,ny,ylow,yup)
{
//*-*-*-*-*-*Normal Constructor for Profile histograms*-*-*-*-*-*-*-*-*-*
//*-*        ==========================================
//
//  The first eight parameters are similar to TH2D::TH2D.
//  All values of z are accepted at filling time.
//  To fill a profile2D histogram, one must use TProfile2D::Fill function.
//
//  Note that when filling the profile histogram the function Fill
//  checks if the variable z is betyween fZmin and fZmax.
//  If a minimum or maximum value is set for the Z scale before filling,
//  then all values below zmin or above zmax will be discarded.
//  Setting the minimum or maximum value for the Z scale before filling
//  has the same effect as calling the special TProfile2D constructor below
//  where zmin and zmax are specified.
//
//  H(I,J) is printed as the cell contents. The errors computed are s(I,J) if CHOPT='S'
//  (spread option), or e(I,J) if CHOPT=' ' (error on mean).
//
//        See TProfile2D::BuildOptions for explanation of parameters
//
//   see other constructors below with all possible combinations of
//   fix and variable bin size like in TH2D.

   BuildOptions(0,0,option);
}

//______________________________________________________________________________
TProfile2D::TProfile2D(const char *name,const char *title,Int_t nx,const Double_t *xbins,Int_t ny,Axis_t ylow,Axis_t yup,Option_t *option)
    : TH2D(name,title,nx,xbins,ny,ylow,yup)
{
//  Create a 2-D Profile with variable bins in X and fix bins in Y
   
   BuildOptions(0,0,option);
}

//______________________________________________________________________________
TProfile2D::TProfile2D(const char *name,const char *title,Int_t nx,Axis_t xlow,Axis_t xup,Int_t ny,const Double_t *ybins,Option_t *option)
    : TH2D(name,title,nx,xlow,xup,ny,ybins)
{
//  Create a 2-D Profile with fix bins in X and variable bins in Y
   
   BuildOptions(0,0,option);
}

//______________________________________________________________________________
TProfile2D::TProfile2D(const char *name,const char *title,Int_t nx,const Double_t *xbins,Int_t ny,const Double_t *ybins,Option_t *option)
    : TH2D(name,title,nx,xbins,ny,ybins)
{
//  Create a 2-D Profile with variable bins in X and variable bins in Y
   
   BuildOptions(0,0,option);
}


//______________________________________________________________________________
TProfile2D::TProfile2D(const char *name,const char *title,Int_t nx,Axis_t xlow,Axis_t xup,Int_t ny, Axis_t ylow,Axis_t yup,Axis_t zlow,Axis_t zup,Option_t *option)
    : TH2D(name,title,nx,xlow,xup,ny,ylow,yup)
{
//*-*-*-*-*-*Constructor for Profile2D histograms with range in z*-*-*-*-*-*
//*-*        ====================================================
//  The first eight parameters are similar to TH2D::TH2D.
//  Only the values of Z between ZMIN and ZMAX will be considered at filling time.
//  zmin and zmax will also be the maximum and minimum values
//  on the z scale when drawing the profile2D.
//
//        See TProfile2D::BuildOptions for more explanations on errors
//

   BuildOptions(zlow,zup,option);
}


//______________________________________________________________________________
void TProfile2D::BuildOptions(Double_t zmin, Double_t zmax, Option_t *option)
{
//*-*-*-*-*-*-*Set Profile2D histogram structure and options*-*-*-*-*-*-*-*-*
//*-*          =============================================
//
//    If a cell has N data points all with the same value Z (especially
//    possible when dealing with integers), the spread in Z for that cell
//    is zero, and the uncertainty assigned is also zero, and the cell is
//    ignored in making subsequent fits. If SQRT(Z) was the correct error
//    in the case above, then SQRT(Z)/SQRT(N) would be the correct error here.
//    In fact, any cell with non-zero number of entries N but with zero spread
//    should have an uncertainty SQRT(Z)/SQRT(N).
//
//    Now, is SQRT(Z)/SQRT(N) really the correct uncertainty?
//    that it is only in the case where the Z variable is some sort
//    of counting statistics, following a Poisson distribution. This should
//    probably be set as the default case. However, Z can be any variable
//    from an original NTUPLE, not necessarily distributed "Poissonly".
//    The computation of errors is based on the parameter option:
//    option:
//     ' '  (Default) Errors are Spread/SQRT(N) for Spread.ne.0. ,
//                      "     "  SQRT(Z)/SQRT(N) for Spread.eq.0,N.gt.0 ,
//                      "     "  0.  for N.eq.0
//     's'            Errors are Spread  for Spread.ne.0. ,
//                      "     "  SQRT(Z)  for Spread.eq.0,N.gt.0 ,
//                      "     "  0.  for N.eq.0
//     'i'            Errors are Spread/SQRT(N) for Spread.ne.0. ,
//                      "     "  1./SQRT(12.*N) for Spread.eq.0,N.gt.0 ,
//                      "     "  0.  for N.eq.0
//
//    The third case above corresponds to Integer Z values for which the
//    uncertainty is +-0.5, with the assumption that the probability that Z
//    takes any value between Z-0.5 and Z+0.5 is uniform (the same argument
//    goes for Z uniformly distributed between Z and Z+1); this would be
//    useful if Z is an ADC measurement, for example. Other, fancier options
//    would be possible, at the cost of adding one more parameter to the PROFILE2D
//    For example, if all Z variables are distributed according to some
//    known Gaussian of standard deviation Sigma, then:
//     'G'            Errors are Spread/SQRT(N) for Spread.ne.0. ,
//                      "     "  Sigma/SQRT(N) for Spread.eq.0,N.gt.0 ,
//                      "     "  0.  for N.eq.0
//    For example, this would be useful when all Z's are experimental quantities
//    measured with the same instrument with precision Sigma.
//
//

   SetErrorOption(option);

   fBinEntries.Set(fNcells);  //*-* create number of entries per cell array

   Sumw2();                   //*-* create sum of squares of weights array

   fZmin = zmin;
   fZmax = zmax;
   fScaling = kFALSE;
   fTsumwz  = fTsumwz2 = 0;
}

//______________________________________________________________________________
TProfile2D::TProfile2D(const TProfile2D &profile) : TH2D()
{
   ((TProfile2D&)profile).Copy(*this);
}


//______________________________________________________________________________
void TProfile2D::Add(TF1 *, Double_t , Option_t*)
{
   // Performs the operation: this = this + c1*f1

   Error("Add","Function not implemented for TProfile2D");
   return;
}


//______________________________________________________________________________
void TProfile2D::Add(const TH1 *h1, Double_t c1)
{
   // Performs the operation: this = this + c1*h1

   if (!h1) {
      Error("Add","Attempt to add a non-existing profile");
      return;
   }
   if (!h1->InheritsFrom("TProfile2D")) {
      Error("Add","Attempt to add a non-profile2D object");
      return;
   }
   TProfile2D *p1 = (TProfile2D*)h1;

//*-*- Check profile compatibility
   Int_t nx = GetNbinsX();
   if (nx != p1->GetNbinsX()) {
      Error("Add","Attempt to add profiles with different number of bins");
      return;
   }
   Int_t ny = GetNbinsY();
   if (ny != p1->GetNbinsY()) {
      Error("Add","Attempt to add profiles with different number of bins");
      return;
   }

//*-*- Add statistics
   Double_t ac1 = TMath::Abs(c1);
   fEntries += ac1*p1->GetEntries();
   fTsumw   += ac1*p1->fTsumw;
   fTsumw2  += ac1*p1->fTsumw2;
   fTsumwx  += ac1*p1->fTsumwx;
   fTsumwx2 += ac1*p1->fTsumwx2;
   fTsumwy  += ac1*p1->fTsumwy;
   fTsumwy2 += ac1*p1->fTsumwy2;
   fTsumwxy += ac1*p1->fTsumwxy;
   fTsumwz  += ac1*p1->fTsumwz;
   fTsumwz2 += ac1*p1->fTsumwz2;

//*-*- Loop on bins (including underflows/overflows)
   Int_t bin,binx,biny;
   Double_t *cu1 = p1->GetW();
   Double_t *er1 = p1->GetW2();
   Double_t *en1 = p1->GetB();
   for (binx =0;binx<=nx+1;binx++) {
      for (biny =0;biny<=ny+1;biny++) {
         bin   = biny*(fXaxis.GetNbins()+2) + binx;
         fArray[bin]             +=  c1*cu1[bin];
         fSumw2.fArray[bin]      += ac1*er1[bin];
         if (!fScaling) fBinEntries.fArray[bin] += ac1*en1[bin];
      }
   }
}

//______________________________________________________________________________
void TProfile2D::Add(const TH1 *h1, const TH1 *h2, Double_t c1, Double_t c2)
{
//*-*-*-*-*Replace contents of this profile2D by the addition of h1 and h2*-*-*
//*-*      ===============================================================
//
//   this = c1*h1 + c2*h2
//

   if (!h1 || !h2) {
      Error("Add","Attempt to add a non-existing profile");
      return;
   }
   if (!h1->InheritsFrom("TProfile2D")) {
      Error("Add","Attempt to add a non-profile2D object");
      return;
   }
   TProfile2D *p1 = (TProfile2D*)h1;
   if (!h2->InheritsFrom("TProfile2D")) {
      Error("Add","Attempt to add a non-profile2D object");
      return;
   }
   TProfile2D *p2 = (TProfile2D*)h2;

//*-*- Check profile compatibility
   Int_t nx = GetNbinsX();
   if (nx != p1->GetNbinsX() || nx != p2->GetNbinsX()) {
      Error("Add","Attempt to add profiles with different number of bins");
      return;
   }
   Int_t ny = GetNbinsY();
   if (ny != p1->GetNbinsY() || ny != p2->GetNbinsY()) {
      Error("Add","Attempt to add profiles with different number of bins");
      return;
   }

//*-*- Add statistics
   Double_t ac1 = TMath::Abs(c1);
   Double_t ac2 = TMath::Abs(c2);
   fEntries = ac1*p1->GetEntries() + ac2*p2->GetEntries();
   fTsumw   = ac1*p1->fTsumw       + ac2*p2->fTsumw;
   fTsumw2  = ac1*p1->fTsumw2      + ac2*p2->fTsumw2;
   fTsumwx  = ac1*p1->fTsumwx      + ac2*p2->fTsumwx;
   fTsumwx2 = ac1*p1->fTsumwx2     + ac2*p2->fTsumwx2;
   fTsumwy  = ac1*p1->fTsumwy      + ac2*p2->fTsumwy;
   fTsumwy2 = ac1*p1->fTsumwy2     + ac2*p2->fTsumwy2;
   fTsumwxy = ac1*p1->fTsumwxy     + ac2*p2->fTsumwxy;
   fTsumwz  = ac1*p1->fTsumwz      + ac2*p2->fTsumwz;
   fTsumwz2 = ac1*p1->fTsumwz2     + ac2*p2->fTsumwz2;

//*-*- Loop on bins (including underflows/overflows)
   Int_t bin,binx,biny;
   Double_t *cu1 = p1->GetW();
   Double_t *cu2 = p2->GetW();
   Double_t *er1 = p1->GetW2();
   Double_t *er2 = p2->GetW2();
   Double_t *en1 = p1->GetB();
   Double_t *en2 = p2->GetB();
   for (binx =0;binx<=nx+1;binx++) {
      for (biny =0;biny<=ny+1;biny++) {
         bin   = biny*(fXaxis.GetNbins()+2) + binx;
         fArray[bin]             =  c1*cu1[bin] +  c2*cu2[bin];
         fSumw2.fArray[bin]      = ac1*er1[bin] + ac2*er2[bin];
         if (fScaling) {
            fBinEntries.fArray[bin] = en1[bin];
         } else {
            fBinEntries.fArray[bin] = ac1*en1[bin] + ac2*en2[bin];
         }
      }
   }
}


//______________________________________________________________________________
void TProfile2D::Approximate(Bool_t approx)
{
//     static function
// set the fgApproximate flag. When the flag is true, the function GetBinError
// will approximate the bin error with the average profile error on all bins
// in the following situation only
//  - the number of bins in the profile2D is less than 10404 (eg 100x100)
//  - the bin number of entries is small ( <5)
//  - the estimated bin error is extremely small compared to the bin content
//  (see TProfile2D::GetBinError)
   
   fgApproximate = approx;
}


//______________________________________________________________________________
Int_t TProfile2D::BufferEmpty(Bool_t deleteBuffer)
{
// Fill histogram with all entries in the buffer.
// The buffer is deleted if deleteBuffer is true.

   // do we need to compute the bin size?
   Int_t nbentries = (Int_t)fBuffer[0];
   if (!nbentries) return 0;
   if (fXaxis.GetXmax() <= fXaxis.GetXmin()) {
      //find min, max of entries in buffer
     Double_t xmin = fBuffer[2];
     Double_t xmax = xmin;
     Double_t ymin = fBuffer[3];
     Double_t ymax = ymin;
    for (Int_t i=1;i<nbentries;i++) {
         Double_t x = fBuffer[4*i+2];
         if (x < xmin) xmin = x;
         if (x > xmax) xmax = x;
         Double_t y = fBuffer[4*i+3];
         if (y < ymin) ymin = y;
         if (y > ymax) ymax = y;
     }
      THLimitsFinder::GetLimitsFinder()->FindGoodLimits(this,xmin,xmax,ymin,ymax);
   }

   Double_t *buffer = fBuffer; fBuffer = 0;

   for (Int_t i=0;i<nbentries;i++) {
      Fill(buffer[4*i+2],buffer[4*i+3],buffer[4*i+4],buffer[4*i+1]);
   }

   if (deleteBuffer) { delete buffer;    fBufferSize = 0;}
   else              { fBuffer = buffer; fBuffer[0] = 0;}
   return nbentries;
}

//______________________________________________________________________________
Int_t TProfile2D::BufferFill(Axis_t x, Axis_t y, Axis_t z, Stat_t w)
{
// accumulate arguments in buffer. When buffer is full, empty the buffer
// fBuffer[0] = number of entries in buffer
// fBuffer[1] = w of first entry
// fBuffer[2] = x of first entry

   Int_t nbentries = (Int_t)fBuffer[0];
   if (nbentries >= fBufferSize) {
      BufferEmpty(kTRUE);
      return Fill(x,y,z,w);
   }
   fBuffer[4*nbentries+1] = w;
   fBuffer[4*nbentries+2] = x;
   fBuffer[4*nbentries+3] = y;
   fBuffer[4*nbentries+4] = z;
   fBuffer[0] += 1;
   return -2;
}

//______________________________________________________________________________
void TProfile2D::Copy(TObject &obj) const
{
//*-*-*-*-*-*-*-*Copy a Profile2D histogram to a new profile2D histogram*-*-*-*
//*-*            =======================================================

   TH2D::Copy(((TProfile2D&)obj));
   fBinEntries.Copy(((TProfile2D&)obj).fBinEntries);
   ((TProfile2D&)obj).fZmin = fZmin;
   ((TProfile2D&)obj).fZmax = fZmax;
   ((TProfile2D&)obj).fScaling = fScaling;
   ((TProfile2D&)obj).fErrorMode = fErrorMode;
   ((TProfile2D&)obj).fTsumwz  = fTsumwz;
   ((TProfile2D&)obj).fTsumwz2 = fTsumwz2;
}


//______________________________________________________________________________
void TProfile2D::Divide(TF1 *, Double_t )
{
   // Performs the operation: this = this/(c1*f1)

   Error("Divide","Function not implemented for TProfile2D");
   return;
}

//______________________________________________________________________________
void TProfile2D::Divide(const TH1 *h1)
{
//*-*-*-*-*-*-*-*-*-*-*Divide this profile2D by h1*-*-*-*-*-*-*-*-*-*-*-*-*
//*-*                  ===========================
//
//   this = this/h1
//

   if (!h1) {
      Error("Divide","Attempt to divide a non-existing profile2D");
      return;
   }
   if (!h1->InheritsFrom("TProfile2D")) {
      Error("Divide","Attempt to divide a non-profile2D object");
      return;
   }
   TProfile2D *p1 = (TProfile2D*)h1;

//*-*- Check profile compatibility
   Int_t nx = GetNbinsX();
   if (nx != p1->GetNbinsX()) {
      Error("Divide","Attempt to divide profiles with different number of bins");
      return;
   }
   Int_t ny = GetNbinsY();
   if (ny != p1->GetNbinsY()) {
      Error("Divide","Attempt to divide profiles with different number of bins");
      return;
   }

//*-*- Reset statistics
   fEntries = fTsumw   = fTsumw2 = fTsumwx = fTsumwx2 = 0;

//*-*- Loop on bins (including underflows/overflows)
   Int_t bin,binx,biny;
   Double_t *cu1 = p1->GetW();
   Double_t *er1 = p1->GetW2();
   Double_t *en1 = p1->GetB();
   Double_t c0,c1,w,z,x,y;
   for (binx =0;binx<=nx+1;binx++) {
      for (biny =0;biny<=ny+1;biny++) {
         bin   = biny*(fXaxis.GetNbins()+2) + binx;
         c0  = fArray[bin];
         c1  = cu1[bin];
         if (c1) w = c0/c1;
         else    w = 0;
         fArray[bin] = w;
         z = TMath::Abs(w);
         x = fXaxis.GetBinCenter(binx);
         y = fYaxis.GetBinCenter(biny);
         fEntries++;
         fTsumw   += z;
         fTsumw2  += z*z;
         fTsumwx  += z*x;
         fTsumwx2 += z*x*x;
         fTsumwy  += z*y;
         fTsumwy2 += z*y*y;
         fTsumwxy += z*x*y;
         fTsumwz  += z;
         fTsumwz2 += z*z;
         Double_t e0 = fSumw2.fArray[bin];
         Double_t e1 = er1[bin];
         Double_t c12= c1*c1;
         if (!c1) fSumw2.fArray[bin] = 0;
         else     fSumw2.fArray[bin] = (e0*e0*c1*c1 + e1*e1*c0*c0)/(c12*c12);
         if (!en1[bin]) fBinEntries.fArray[bin] = 0;
         else           fBinEntries.fArray[bin] /= en1[bin];
      }
   }
}


//______________________________________________________________________________
void TProfile2D::Divide(const TH1 *h1, const TH1 *h2, Double_t c1, Double_t c2, Option_t *option)
{
//*-*-*-*-*Replace contents of this profile2D by the division of h1 by h2*-*-*
//*-*      ==============================================================
//
//   this = c1*h1/(c2*h2)
//

   TString opt = option;
   opt.ToLower();
   Bool_t binomial = kFALSE;
   if (opt.Contains("b")) binomial = kTRUE;
   if (!h1 || !h2) {
      Error("Divide","Attempt to divide a non-existing profile2D");
      return;
   }
   if (!h1->InheritsFrom("TProfile2D")) {
      Error("Divide","Attempt to divide a non-profile2D object");
      return;
   }
   TProfile2D *p1 = (TProfile2D*)h1;
   if (!h2->InheritsFrom("TProfile2D")) {
      Error("Divide","Attempt to divide a non-profile2D object");
      return;
   }
   TProfile2D *p2 = (TProfile2D*)h2;

//*-*- Check histogram compatibility
   Int_t nx = GetNbinsX();
   if (nx != p1->GetNbinsX() || nx != p2->GetNbinsX()) {
      Error("Divide","Attempt to divide profiles with different number of bins");
      return;
   }
   Int_t ny = GetNbinsY();
   if (ny != p1->GetNbinsY() || ny != p2->GetNbinsY()) {
      Error("Divide","Attempt to divide profiles with different number of bins");
      return;
   }
   if (!c2) {
      Error("Divide","Coefficient of dividing profile cannot be zero");
      return;
   }

//*-*- Reset statistics
   fEntries = fTsumw   = fTsumw2 = fTsumwx = fTsumwx2 = 0;

//*-*- Loop on bins (including underflows/overflows)
   Int_t bin,binx,biny;
   Double_t *cu1 = p1->GetW();
   Double_t *cu2 = p2->GetW();
   Double_t *er1 = p1->GetW2();
   Double_t *er2 = p2->GetW2();
   Double_t *en1 = p1->GetB();
   Double_t *en2 = p2->GetB();
   Double_t b1,b2,w,z,x,y,d1,d2;
   d1 = c1*c1;
   d2 = c2*c2;
   for (binx =0;binx<=nx+1;binx++) {
      for (biny =0;biny<=ny+1;biny++) {
         bin   = biny*(fXaxis.GetNbins()+2) + binx;
         b1  = cu1[bin];
         b2  = cu2[bin];
         if (b2) w = c1*b1/(c2*b2);
         else    w = 0;
         fArray[bin] = w;
         z = TMath::Abs(w);
         x = fXaxis.GetBinCenter(binx);
         y = fYaxis.GetBinCenter(biny);
         fEntries++;
         fTsumw   += z;
         fTsumw2  += z*z;
         fTsumwx  += z*x;
         fTsumwx2 += z*x*x;
         fTsumwy  += z*y;
         fTsumwy2 += z*y*y;
         fTsumwxy += z*x*y;
         fTsumwz  += z;
         fTsumwz2 += z*z;
         Double_t e1 = er1[bin];
         Double_t e2 = er2[bin];
         Double_t b22= b2*b2*d2;
         if (!b2) fSumw2.fArray[bin] = 0;
         else {
            if (binomial) {
               fSumw2.fArray[bin] = TMath::Abs(w*(1-w)/(c2*b2));
            } else {
               fSumw2.fArray[bin] = d1*d2*(e1*e1*b2*b2 + e2*e2*b1*b1)/(b22*b22);
            }
         }
         if (!en2[bin]) fBinEntries.fArray[bin] = 0;
         else           fBinEntries.fArray[bin] = en1[bin]/en2[bin];
      }
   }
}

//______________________________________________________________________________
TH1 *TProfile2D::DrawCopy(Option_t *option) const
{
//*-*-*-*-*-*-*-*Draw a copy of this profile2D histogram*-*-*-*-*-*-*-*-*-*-*
//*-*            =======================================
   TProfile2D *newpf = new TProfile2D();
   Copy(*newpf);
   newpf->SetDirectory(0);
   newpf->SetBit(kCanDelete);
   newpf->AppendPad(option);
   return newpf;
}

//______________________________________________________________________________
Int_t TProfile2D::Fill(Axis_t x, Axis_t y, Axis_t z)
{
//*-*-*-*-*-*-*-*-*-*-*Fill a Profile2D histogram (no weights)*-*-*-*-*-*-*-*
//*-*                  =======================================

   if (fBuffer) return BufferFill(x,y,z,1);

   Int_t bin,binx,biny;

   if (fZmin != fZmax) {
      if (z <fZmin || z> fZmax) return -1;
   }

   fEntries++;
   binx =fXaxis.FindBin(x);
   biny =fYaxis.FindBin(y);
   bin  = biny*(fXaxis.GetNbins()+2) + binx;
   AddBinContent(bin, z);
   fSumw2.fArray[bin] += (Stat_t)z*z;
   fBinEntries.fArray[bin] += 1;
   if (binx == 0 || binx > fXaxis.GetNbins()) {
      if (!fgStatOverflows) return -1;
   }
   if (biny == 0 || biny > fYaxis.GetNbins()) {
      if (!fgStatOverflows) return -1;
   }
   ++fTsumw;
   ++fTsumw2;
   fTsumwx  += x;
   fTsumwx2 += x*x;
   fTsumwy  += y;
   fTsumwy2 += y*y;
   fTsumwxy += x*y;
   fTsumwz  += z;
   fTsumwz2 += z*z;
   return bin;
}

//______________________________________________________________________________
Int_t TProfile2D::Fill(Axis_t x, const char *namey, Axis_t z)
{
// Fill a Profile2D histogram (no weights)
//
   Int_t bin,binx,biny;

   if (fZmin != fZmax) {
      if (z <fZmin || z> fZmax) return -1;
   }

   fEntries++;
   binx =fXaxis.FindBin(x);
   biny =fYaxis.FindBin(namey);
   bin  = biny*(fXaxis.GetNbins()+2) + binx;
   AddBinContent(bin, z);
   fSumw2.fArray[bin] += (Stat_t)z*z;
   fBinEntries.fArray[bin] += 1;
   if (binx == 0 || binx > fXaxis.GetNbins()) {
      if (!fgStatOverflows) return -1;
   }
   if (biny == 0 || biny > fYaxis.GetNbins()) return -1;
   Axis_t y = fYaxis.GetBinCenter(biny);
   ++fTsumw;
   ++fTsumw2;
   fTsumwx  += x;
   fTsumwx2 += x*x;
   fTsumwy  += y;
   fTsumwy2 += y*y;
   fTsumwxy += x*y;
   fTsumwz  += z;
   fTsumwz2 += z*z;
   return bin;
}

//______________________________________________________________________________
Int_t TProfile2D::Fill(const char *namex, const char *namey, Axis_t z)
{
// Fill a Profile2D histogram (no weights)
//
   Int_t bin,binx,biny;

   if (fZmin != fZmax) {
      if (z <fZmin || z> fZmax) return -1;
   }

   fEntries++;
   binx =fXaxis.FindBin(namex);
   biny =fYaxis.FindBin(namey);
   bin  = biny*(fXaxis.GetNbins()+2) + binx;
   AddBinContent(bin, z);
   fSumw2.fArray[bin] += (Stat_t)z*z;
   fBinEntries.fArray[bin] += 1;
   if (binx == 0 || binx > fXaxis.GetNbins()) return -1;
   if (biny == 0 || biny > fYaxis.GetNbins()) return -1;
   Axis_t x = fYaxis.GetBinCenter(binx);
   Axis_t y = fYaxis.GetBinCenter(biny);
   ++fTsumw;
   ++fTsumw2;
   fTsumwx  += x;
   fTsumwx2 += x*x;
   fTsumwy  += y;
   fTsumwy2 += y*y;
   fTsumwxy += x*y;
   fTsumwz  += z;
   fTsumwz2 += z*z;
   return bin;
}

//______________________________________________________________________________
Int_t TProfile2D::Fill(const char *namex, Axis_t y, Axis_t z)
{
// Fill a Profile2D histogram (no weights)
//
   Int_t bin,binx,biny;

   if (fZmin != fZmax) {
      if (z <fZmin || z> fZmax) return -1;
   }

   fEntries++;
   binx =fXaxis.FindBin(namex);
   biny =fYaxis.FindBin(y);
   bin  = biny*(fXaxis.GetNbins()+2) + binx;
   AddBinContent(bin, z);
   fSumw2.fArray[bin] += (Stat_t)z*z;
   fBinEntries.fArray[bin] += 1;
   if (binx == 0 || binx > fXaxis.GetNbins()) return -1;
   if (biny == 0 || biny > fYaxis.GetNbins()) {
      if (!fgStatOverflows) return -1;
   }
   Axis_t x = fYaxis.GetBinCenter(binx);
   ++fTsumw;
   ++fTsumw2;
   fTsumwx  += x;
   fTsumwx2 += x*x;
   fTsumwy  += y;
   fTsumwy2 += y*y;
   fTsumwxy += x*y;
   fTsumwz  += z;
   fTsumwz2 += z*z;
   return bin;
}

//______________________________________________________________________________
Int_t TProfile2D::Fill(Axis_t x, Axis_t y, Axis_t z, Stat_t w)
{
//*-*-*-*-*-*-*-*-*-*-*Fill a Profile2D histogram with weights*-*-*-*-*-*-*-*
//*-*                  =======================================

   if (fBuffer) return BufferFill(x,y,z,w);

   Int_t bin,binx,biny;

   if (fZmin != fZmax) {
      if (z <fZmin || z> fZmax) return -1;
   }

   Stat_t u= (w > 0 ? w : -w);
   fEntries++;
   binx =fXaxis.FindBin(x);
   biny =fYaxis.FindBin(y);
   bin  = biny*(fXaxis.GetNbins()+2) + binx;
   AddBinContent(bin, u*z);
   fSumw2.fArray[bin] += u*z*z;
   fBinEntries.fArray[bin] += w;
   if (binx == 0 || binx > fXaxis.GetNbins()) {
      if (!fgStatOverflows) return -1;
   }
   if (biny == 0 || biny > fYaxis.GetNbins()) {
      if (!fgStatOverflows) return -1;
   }
   fTsumw   += u;
   fTsumw2  += u*u;
   fTsumwx  += u*x;
   fTsumwx2 += u*x*x;
   fTsumwy  += u*y;
   fTsumwy2 += u*y*y;
   fTsumwxy += u*x*y;
   fTsumwz  += u*z;
   fTsumwz2 += u*z*z;
   return bin;
}

//______________________________________________________________________________
Stat_t TProfile2D::GetBinContent(Int_t bin) const
{
//*-*-*-*-*-*-*Return bin content of a Profile2D histogram*-*-*-*-*-*-*-*-*
//*-*          ===========================================

   if (fBuffer) ((TProfile2D*)this)->BufferEmpty();

   if (bin < 0 || bin >= fNcells) return 0;
   if (fBinEntries.fArray[bin] == 0) return 0;
   if (!fArray) return 0;
   return fArray[bin]/fBinEntries.fArray[bin];
}

//______________________________________________________________________________
Stat_t TProfile2D::GetBinEntries(Int_t bin) const
{
//*-*-*-*-*-*-*Return bin entries of a Profile2D histogram*-*-*-*-*-*-*-*-*
//*-*          ===========================================

   if (fBuffer) ((TProfile2D*)this)->BufferEmpty();

   if (bin < 0 || bin >= fNcells) return 0;
   return fBinEntries.fArray[bin];
}

//______________________________________________________________________________
Stat_t TProfile2D::GetBinError(Int_t bin) const
{
//*-*-*-*-*-*-*Return bin error of a Profile2D histogram*-*-*-*-*-*-*-*-*
//
// Computing errors: A moving field
// =================================
// The computation of errors for a TProfile2D has evolved with the versions
// of ROOT. The difficulty is in computing errors for bins with low statistics.
// - prior to version 3.10, we had no special treatment of low statistic bins.
//   As a result, these bins had huge errors. The reason is that the
//   expression eprim2 is very close to 0 (rounding problems) or 0.
// - The algorithm is modified/protected for the case
//   when a TProfile2D is projected (ProjectionX). The previous algorithm
//   generated a N^2 problem when projecting a TProfile2D with a large number of 
//   bins (eg 100000).
// - in version 3.10/02, a new static function TProfile::Approximate
//   is introduced to enable or disable (default) the approximation.
//   (see also comments in TProfile::GetBinError)
   
   if (fBuffer) ((TProfile2D*)this)->BufferEmpty();

   if (bin < 0 || bin >= fNcells) return 0;
   Stat_t cont = fArray[bin];
   Stat_t sum  = fBinEntries.fArray[bin];
   Stat_t err2 = fSumw2.fArray[bin];
   if (sum == 0) return 0;
   Stat_t eprim;
   Stat_t contsum = cont/sum;
   Stat_t eprim2  = TMath::Abs(err2/sum - contsum*contsum);
   eprim          = TMath::Sqrt(eprim2);
   Double_t test = 1;
   if (err2 != 0 && sum < 5) test = eprim2*sum/err2;
   //if (eprim <= 0) { //was in 3.10/01
   if (fgApproximate && fNcells <=10404 && (test < 1.e-4 || eprim2 < 1e-6)) { //in 3.10/02
      Stat_t scont, ssum, serr2;
      scont = ssum = serr2 = 0;
      for (Int_t i=1;i<fNcells;i++) {
         if (fSumw2.fArray[i] <= 0) continue; //added in 3.10/02
         scont += fArray[i];
         ssum  += fBinEntries.fArray[i];
         serr2 += fSumw2.fArray[i];
      }
      Stat_t scontsum = scont/ssum;
      Stat_t seprim2  = TMath::Abs(serr2/ssum - scontsum*scontsum);
      eprim           = TMath::Sqrt(seprim2);
   }
   if (fErrorMode == kERRORMEAN) return eprim/TMath::Sqrt(sum);
   else if (fErrorMode == kERRORSPREAD) return eprim;
   else if (fErrorMode == kERRORSPREADI) {
      if (eprim != 0) return eprim/TMath::Sqrt(sum);
      return 1/TMath::Sqrt(12*sum);
   }
   else if (fErrorMode == kERRORSPREADG) {
      return eprim/TMath::Sqrt(sum);
   }
   else return eprim;
}

//______________________________________________________________________________
Option_t *TProfile2D::GetErrorOption() const
{
//*-*-*-*-*-*-*-*-*-*Return option to compute profile2D errors*-*-*-*-*-*-*-*
//*-*                =========================================

   if (fErrorMode == kERRORSPREAD)  return "s";
   if (fErrorMode == kERRORSPREADI) return "i";
   if (fErrorMode == kERRORSPREADG) return "g";
   return "";
}

//______________________________________________________________________________
void TProfile2D::GetStats(Stat_t *stats) const
{
   // fill the array stats from the contents of this profile
   // The array stats must be correctly dimensionned in the calling program.
   // stats[0] = sumw
   // stats[1] = sumw2
   // stats[2] = sumwx
   // stats[3] = sumwx2
   // stats[4] = sumwy
   // stats[5] = sumwy2
   // stats[6] = sumwxy
   // stats[7] = sumwz
   // stats[8] = sumwz2
   //
   // The function recomputes the statistics quantities
   // from the bin contents in the current axis range.

   // Loop on bins
   Int_t bin, binx, biny;
   Stat_t w;
   Axis_t x,y;
   for (bin=0;bin<9;bin++) stats[bin] = 0;
   if (!fBinEntries.fArray) return;
   for (biny=fYaxis.GetFirst();biny<=fYaxis.GetLast();biny++) {
      y = fYaxis.GetBinCenter(biny);
      for (binx=fXaxis.GetFirst();binx<=fXaxis.GetLast();binx++) {
         bin = GetBin(binx,biny);
         w         = fBinEntries.fArray[bin];
         x         = fXaxis.GetBinCenter(binx);
         stats[0] += w;
         stats[1] += w*w;
         stats[2] += w*x;
         stats[3] += w*x*x;
         stats[4] += w*y;
         stats[5] += w*y*y;
         stats[6] += w*x*y;
         stats[7] += fArray[bin];
         stats[8] += fSumw2.fArray[bin];
      }
   }
}

//___________________________________________________________________________
void TProfile2D::LabelsDeflate(Option_t *ax)
{
// Reduce the number of bins for this axis to the number of bins having a label.

   TAxis *axis = GetXaxis();
   if (ax[0] == 'y' || ax[0] == 'Y') axis = GetYaxis();
   if (!axis->GetLabels()) return;
   TIter next(axis->GetLabels());
   TObject *obj;
   Int_t nbins = 0;
   while ((obj = next())) {
      if (obj->GetUniqueID()) nbins++;
   }
   if (nbins < 2) nbins = 2;
   TProfile2D *hold = (TProfile2D*)Clone();
   hold->SetDirectory(0);

   Int_t  nbxold = fXaxis.GetNbins();
   Double_t xmin = axis->GetXmin();
   Double_t xmax = axis->GetBinUpEdge(nbins);
   axis->SetRange(0,0);
   axis->Set(nbins,xmin,xmax);
   Int_t  nbinsx = fXaxis.GetNbins();
   Int_t  nbinsy = fYaxis.GetNbins();
   Int_t ncells = (nbinsx+2)*(nbinsy+2);
   SetBinsLength(ncells);
   fBinEntries.Set(ncells);
   fSumw2.Set(ncells);

   //now loop on all bins and refill
   Int_t bin,ibin,binx,biny;
   for (biny=1;biny<=nbinsy;biny++) {
      for (binx=1;binx<=nbinsx;binx++) {
         bin   = biny*(nbxold+2) + binx;
         ibin  = biny*(nbinsx+2) + binx;
         fArray[ibin] = hold->fArray[bin];
         fBinEntries.fArray[ibin] = hold->fBinEntries.fArray[bin];
         fSumw2.fArray[ibin] = hold->fSumw2.fArray[bin];
      }
   }
   delete hold;
}

//___________________________________________________________________________
void TProfile2D::LabelsInflate(Option_t *ax)
{
// Double the number of bins for axis.
// Refill histogram
// This function is called by TAxis::FindBin(const char *label)

   TAxis *axis = GetXaxis();
   if (ax[0] == 'y' || ax[0] == 'Y') axis = GetYaxis();
   TProfile2D *hold = (TProfile2D*)Clone();
   hold->SetDirectory(0);

   Int_t  nbxold = fXaxis.GetNbins();
   Int_t  nbyold = fYaxis.GetNbins();
   Int_t  nbins  = axis->GetNbins();
   Double_t xmin = axis->GetXmin();
   Double_t xmax = axis->GetXmax();
   xmax = xmin + 2*(xmax-xmin);
   axis->SetRange(0,0);
   axis->Set(2*nbins,xmin,xmax);
   nbins *= 2;
   Int_t  nbinsx = fXaxis.GetNbins();
   Int_t  nbinsy = fYaxis.GetNbins();
   Int_t ncells = (nbinsx+2)*(nbinsy+2);
   SetBinsLength(ncells);
   fBinEntries.Set(ncells);
   fSumw2.Set(ncells);

   //now loop on all bins and refill
   Int_t bin,ibin,binx,biny;
   for (biny=1;biny<=nbinsy;biny++) {
      for (binx=1;binx<=nbinsx;binx++) {
         bin   = biny*(nbxold+2) + binx;
         ibin  = biny*(nbinsx+2) + binx;
         if (binx <= nbxold && biny <= nbyold) {
            fArray[ibin] = hold->fArray[bin];
            fBinEntries.fArray[ibin] = hold->fBinEntries.fArray[bin];
            fSumw2.fArray[ibin] = hold->fSumw2.fArray[bin];
         } else {
            fArray[ibin] = 0;
            fBinEntries.fArray[ibin] = 0;
            fSumw2.fArray[ibin] = 0;
         }
      }
   }
   delete hold;
}

//___________________________________________________________________________
void TProfile2D::LabelsOption(Option_t *option, Option_t *ax)
{
//  Set option(s) to draw axis with labels
//  option = "a" sort by alphabetic order
//         = ">" sort by decreasing values
//         = "<" sort by increasing values
//         = "h" draw labels horizonthal
//         = "v" draw labels vertical
//         = "u" draw labels up (end of label right adjusted)
//         = "d" draw labels down (start of label left adjusted)

   TAxis *axis = GetXaxis();
   if (ax[0] == 'y' || ax[0] == 'Y') axis = GetYaxis();
   THashList *labels = axis->GetLabels();
   if (!labels) {
      Warning("LabelsOption","Cannot sort. No labels");
      return;
   }
   TString opt = option;
   opt.ToLower();
   if (opt.Contains("h")) {
      fXaxis.SetBit(TAxis::kLabelsHori);
      fXaxis.ResetBit(TAxis::kLabelsVert);
      fXaxis.ResetBit(TAxis::kLabelsDown);
      fXaxis.ResetBit(TAxis::kLabelsUp);
   }
    if (opt.Contains("v")) {
      fXaxis.SetBit(TAxis::kLabelsVert);
      fXaxis.ResetBit(TAxis::kLabelsHori);
      fXaxis.ResetBit(TAxis::kLabelsDown);
      fXaxis.ResetBit(TAxis::kLabelsUp);
   }
   if (opt.Contains("u")) {
      fXaxis.SetBit(TAxis::kLabelsUp);
      fXaxis.ResetBit(TAxis::kLabelsVert);
      fXaxis.ResetBit(TAxis::kLabelsDown);
      fXaxis.ResetBit(TAxis::kLabelsHori);
   }
   if (opt.Contains("d")) {
      fXaxis.SetBit(TAxis::kLabelsDown);
      fXaxis.ResetBit(TAxis::kLabelsVert);
      fXaxis.ResetBit(TAxis::kLabelsHori);
      fXaxis.ResetBit(TAxis::kLabelsUp);
   }
   Int_t sort = -1;
   if (opt.Contains("a")) sort = 0;
   if (opt.Contains(">")) sort = 1;
   if (opt.Contains("<")) sort = 2;
   if (sort < 0) return;

   Int_t nx = fXaxis.GetNbins()+2;
   Int_t ny = fYaxis.GetNbins()+2;
   Int_t n = TMath::Min(axis->GetNbins(), labels->GetSize());
   Int_t *a = new Int_t[n+2];
   Int_t i,j,k,bin;
   Double_t *sumw   = new Double_t[nx*ny];
   Double_t *errors = new Double_t[nx*ny];
   Double_t *ent    = new Double_t[nx*ny];
   THashList *labold = new THashList(labels->GetSize(),1);
   TIter nextold(labels);
   TObject *obj;
   while ((obj=nextold())) {
      labold->Add(obj);
   }
   labels->Clear();
   if (sort > 0) {
      //---sort by values of bins
      Double_t *pcont = new Double_t[n+2];
      for (i=0;i<=n;i++) pcont[i] = 0;
      for (i=1;i<nx;i++) {
         for (j=1;j<ny;j++) {
            bin = i+nx*j;
            sumw[bin]   = fArray[bin];
            errors[bin] = fSumw2.fArray[bin];
            ent[bin]    = fBinEntries.fArray[bin];
            if (axis == GetXaxis()) k = i;
            else                    k = j;
            if (fBinEntries.fArray[bin] != 0) pcont[k-1] += fArray[bin]/fBinEntries.fArray[bin];
         }
      }
      if (sort ==1) TMath::Sort(n,pcont,a,kTRUE);  //sort by decreasing values
      else          TMath::Sort(n,pcont,a,kFALSE); //sort by increasing values
      delete [] pcont;
      for (i=0;i<n;i++) {
         obj = labold->At(a[i]);
         labels->Add(obj);
         obj->SetUniqueID(i+1);
      }
      for (i=1;i<nx;i++) {
         for (j=1;j<ny;j++) {
            bin = i+nx*j;
            if (axis == GetXaxis()) {
               fArray[bin] = sumw[a[i-1]+1+nx*j];
               fSumw2.fArray[bin] = errors[a[i-1]+1+nx*j];
               fBinEntries.fArray[bin] = ent[a[i-1]+1+nx*j];
            } else {
               fArray[bin] = sumw[i+nx*(a[j-1]+1)];
               fSumw2.fArray[bin] = errors[i+nx*(a[j-1]+1)];
               fBinEntries.fArray[bin] = ent[i+nx*(a[j-1]+1)];
            }
         }
      }
   } else {
      //---alphabetic sort
      const UInt_t kUsed = 1<<18;
      TObject *objk=0;
      a[0] = 0;
      a[n+1] = n+1;
      for (i=1;i<=n;i++) {
         const char *label = "zzzzzzzzzzzz";
         for (j=1;j<=n;j++) {
            obj = labold->At(j-1);
            if (!obj) continue;
            if (obj->TestBit(kUsed)) continue;
            //use strcasecmp for case non-sensitive sort (may be an option)
            if (strcmp(label,obj->GetName()) < 0) continue;
            objk = obj;
            a[i] = j;
            label = obj->GetName();
         }
         if (objk) {
            objk->SetUniqueID(i);
            labels->Add(objk);
            objk->SetBit(kUsed);
         }
      }
      for (i=1;i<=n;i++) {
         obj = labels->At(i-1);
         if (!obj) continue;
         obj->ResetBit(kUsed);
      }
      for (i=0;i<nx;i++) {
         for (j=0;j<ny;j++) {
            bin = i+nx*j;
            sumw[bin]   = fArray[bin];
            errors[bin] = fSumw2.fArray[bin];
            ent[bin]    = fBinEntries.fArray[bin];
         }
      }
      for (i=0;i<nx;i++) {
         for (j=0;j<ny;j++) {
            bin = i+nx*j;
            if (axis == GetXaxis()) {
               fArray[bin] = sumw[a[i]+nx*j];
               fSumw2.fArray[bin] = errors[a[i]+nx*j];
               fBinEntries.fArray[bin] = ent[a[i]+nx*j];
            } else {
               fArray[bin] = sumw[i+nx*a[j]];
               fSumw2.fArray[bin] = errors[i+nx*a[j]];
               fBinEntries.fArray[bin] = ent[i+nx*a[j]];
            }
         }
      }
   }
   delete labold;
   if (a)      delete [] a;
   if (sumw)   delete [] sumw;
   if (errors) delete [] errors;
   if (ent)    delete [] ent;
}

//______________________________________________________________________________
Int_t TProfile2D::Merge(TCollection *list)
{
   //Merge all histograms in the collection in this histogram.
   //This function computes the min/max for the axes,
   //compute a new number of bins, if necessary,
   //add bin contents, errors and statistics.
   //The function returns the merged number of entries if the merge is
   //successfull, -1 otherwise.
   //
   //IMPORTANT remark. The 2 axis x and y may have different number
   //of bins and different limits, BUT the largest bin width must be
   //a multiple of the smallest bin width.

   if (!list) return 0;
   TIter next(list);
   Double_t umin,umax,vmin,vmax;
   Int_t nx,ny;
   Double_t xmin  = fXaxis.GetXmin();
   Double_t xmax  = fXaxis.GetXmax();
   Double_t ymin  = fYaxis.GetXmin();
   Double_t ymax  = fYaxis.GetXmax();
   Double_t bwix  = fXaxis.GetBinWidth(1);
   Double_t bwiy  = fYaxis.GetBinWidth(1);
   Int_t    nbix  = fXaxis.GetNbins();
   Int_t    nbiy  = fYaxis.GetNbins();

   TProfile2D *h;
   Int_t nentries=0;
   Bool_t same = kTRUE;
   while ((h=(TProfile2D*)next())) {
      if (!h->InheritsFrom(TProfile2D::Class())) {
         Error("Add","Attempt to add object of class: %s to a %s",h->ClassName(),this->ClassName());
         return -1;
      }
      //import statistics
      nentries += (Int_t)h->GetEntries();

      // find min/max of the axes
      umin = h->GetXaxis()->GetXmin();
      umax = h->GetXaxis()->GetXmax();
      vmin = h->GetYaxis()->GetXmin();
      vmax = h->GetYaxis()->GetXmax();
      nx   = h->GetXaxis()->GetNbins();
      ny   = h->GetYaxis()->GetNbins();
      if (nx != nbix || ny != nbiy ||
              umin != xmin || umax != xmax || vmin != ymin || vmax != ymax) {
         same = kFALSE;
         if (umin < xmin) xmin = umin;
         if (umax > xmax) xmax = umax;
         if (vmin < ymin) ymin = vmin;
         if (vmax > ymax) ymax = vmax;
         if (h->GetXaxis()->GetBinWidth(1) > bwix) bwix = h->GetXaxis()->GetBinWidth(1);
         if (h->GetYaxis()->GetBinWidth(1) > bwiy) bwiy = h->GetYaxis()->GetBinWidth(1);
      }
   }

   //  if different binning compute best binning
   if (!same) {
      nbix = (Int_t) ((xmax-xmin)/bwix +0.1); while(nbix > 100) nbix /= 2;
      nbiy = (Int_t) ((ymax-ymin)/bwiy +0.1); while(nbiy > 100) nbiy /= 2;
      SetBins(nbix,xmin,xmax,nbiy,ymin,ymax);
   }

   //merge bin contents and errors
   next.Reset();
   Int_t ibin, bin, binx, biny, ix, iy;
   while ((h=(TProfile2D*)next())) {
      nx   = h->GetXaxis()->GetNbins();
      ny   = h->GetYaxis()->GetNbins();
      for (biny=0;biny<=ny+1;biny++) {
         iy = fYaxis.FindBin(h->GetBinCenter(biny));
         for (binx=0;binx<=nx+1;binx++) {
            ix = fXaxis.FindBin(h->GetBinCenter(binx));
            bin = binx +(nx+2)*biny;
            ibin = ix +(nbix+2)*iy;
            fArray[ibin]             += h->GetW()[bin];
            fSumw2.fArray[ibin]      += h->GetW2()[bin];
            fBinEntries.fArray[ibin] += h->GetB()[bin];
         }
      }
      fEntries += h->GetEntries();
      fTsumw   += h->fTsumw;
      fTsumw2  += h->fTsumw2;
      fTsumwx  += h->fTsumwx;
      fTsumwx2 += h->fTsumwx2;
      fTsumwy  += h->fTsumwy;
      fTsumwy2 += h->fTsumwy2;
      fTsumwxy += h->fTsumwxy;
      fTsumwz  += h->fTsumwz;
      fTsumwz2 += h->fTsumwz2;
  }

   return nentries;
}

//______________________________________________________________________________
void TProfile2D::Multiply(TF1 *, Double_t )
{
   // Performs the operation: this = this*c1*f1

   Error("Multiply","Function not implemented for TProfile2D");
   return;
}

//______________________________________________________________________________
void TProfile2D::Multiply(const TH1 *)
{
//*-*-*-*-*-*-*-*-*-*-*Multiply this profile2D by h1*-*-*-*-*-*-*-*-*-*-*-*
//*-*                  =============================
//
//   this = this*h1
//
   Error("Multiply","Multiplication of profile2D histograms not implemented");
}


//______________________________________________________________________________
void TProfile2D::Multiply(const TH1 *, const TH1 *, Double_t, Double_t, Option_t *)
{
//*-*-*-*-*Replace contents of this profile2D by multiplication of h1 by h2*-*
//*-*      ================================================================
//
//   this = (c1*h1)*(c2*h2)
//

   Error("Multiply","Multiplication of profile2D histograms not implemented");
}

//______________________________________________________________________________
TH2D *TProfile2D::ProjectionXY(const char *name, Option_t *option) const
{
//*-*-*-*-*Project this profile2D into a 2-D histogram along X,Y*-*-*-*-*-*-*
//*-*      =====================================================
//
//   The projection is always of the type TH2D.
//
//   if option "E" is specified, the errors are computed. (default)
//
//

  TString opt = option;
  opt.ToLower();
  Int_t nx = fXaxis.GetNbins();
  Int_t ny = fYaxis.GetNbins();

// Create the projection histogram
  char *pname = (char*)name;
  if (strcmp(name,"_px") == 0) {
     Int_t nch = strlen(GetName()) + 4;
     pname = new char[nch];
     sprintf(pname,"%s%s",GetName(),name);
  }
  TH2D *h1 = new TH2D(pname,GetTitle(),nx,fXaxis.GetXmin(),fXaxis.GetXmax(),ny,fYaxis.GetXmin(),fYaxis.GetXmax());
  Bool_t computeErrors = kFALSE;
  if (opt.Contains("e")) {h1->Sumw2(); computeErrors = kTRUE;}
  if (pname != name)  delete [] pname;

// Fill the projected histogram
  Int_t bin, binx, biny;
  Double_t cont,err;
  for (binx =0;binx<=nx+1;binx++) {
     for (biny =0;biny<=ny+1;biny++) {
        bin   = biny*(fXaxis.GetNbins()+2) + binx;
        cont  = GetBinContent(bin);
        err   = GetBinError(bin);
        if (cont)          h1->Fill(fXaxis.GetBinCenter(binx),fYaxis.GetBinCenter(biny), cont);
        if (computeErrors) h1->SetBinError(bin,err);
     }
  }
  h1->SetEntries(fEntries);
  return h1;
}

//______________________________________________________________________________
void TProfile2D::Reset(Option_t *option)
{
//*-*-*-*-*-*-*-*-*-*Reset contents of a Profile2D histogram*-*-*-*-*-*-*-*
//*-*                =======================================
  TH2D::Reset(option);
  fBinEntries.Reset();
  fTsumwz = fTsumwz2 = 0;  
}

//______________________________________________________________________________
void TProfile2D::SavePrimitive(ofstream &out, Option_t *option)
{
   // Save primitive as a C++ statement(s) on output stream out

   //Note the following restrictions in the code generated:
   // - variable bin size not implemented
   // - SetErrorOption not implemented


   char quote = '"';
   out <<"   "<<endl;
   out <<"   "<<"ClassName()"<<" *";

   out << GetName() << " = new " << ClassName() << "(" << quote
       << GetName() << quote << "," << quote<< GetTitle() << quote
       << "," << GetXaxis()->GetNbins();
   out << "," << GetXaxis()->GetXmin()
       << "," << GetXaxis()->GetXmax();
   out << "," << GetYaxis()->GetNbins();
   out << "," << GetYaxis()->GetXmin()
       << "," << GetYaxis()->GetXmax();
   out << "," << fZmin
       << "," << fZmax;
   out << ");" << endl;
   

   // save bin entries
   Int_t bin;
   for (bin=0;bin<fNcells;bin++) {
      Double_t bi = GetBinEntries(bin);
      if (bi) {
         out<<"   "<<GetName()<<"->SetBinEntries("<<bin<<","<<bi<<");"<<endl;
      }
   }
   //save bin contents
   for (bin=0;bin<fNcells;bin++) {
      Double_t bc = fArray[bin];
      if (bc) {
         out<<"   "<<GetName()<<"->SetBinContent("<<bin<<","<<bc<<");"<<endl;
      }
   }
   // save bin errors
   if (fSumw2.fN) {
      for (bin=0;bin<fNcells;bin++) {
         Double_t be = TMath::Sqrt(fSumw2.fArray[bin]);
         if (be) {
            out<<"   "<<GetName()<<"->SetBinError("<<bin<<","<<be<<");"<<endl;
         }
      }
   }
   
   TH1::SavePrimitiveHelp(out, option);
}

//______________________________________________________________________________
void TProfile2D::Scale(Double_t c1)
{
//*-*-*-*-*Multiply this profile2D by a constant c1*-*-*-*-*-*-*-*-*
//*-*      ========================================
//
//   this = c1*this
//
// This function uses the services of TProfile2D::Add
//

   Double_t ent = fEntries;
   fScaling = kTRUE;
   Add(this,this,c1,0);
   fScaling = kFALSE;
   fEntries = ent;
}

//______________________________________________________________________________
void TProfile2D::SetBinEntries(Int_t bin, Stat_t w)
{
//*-*-*-*-*-*-*-*-*Set the number of entries in bin*-*-*-*-*-*-*-*-*-*-*-*
//*-*              ================================

   if (bin < 0 || bin >= fNcells) return;
   fBinEntries.fArray[bin] = w;
}

//______________________________________________________________________________
void TProfile2D::SetBins(Int_t nx, Double_t xmin, Double_t xmax, Int_t ny, Double_t ymin, Double_t ymax)
{
//*-*-*-*-*-*-*-*-*Redefine  x axis parameters*-*-*-*-*-*-*-*-*-*-*-*
//*-*              ===========================

   fXaxis.Set(nx,xmin,xmax);
   fYaxis.Set(ny,ymin,ymax);
   fNcells = (nx+2)*(ny+2);
   fBinEntries.Set(fNcells);
   fSumw2.Set(fNcells);
}


//______________________________________________________________________________
void TProfile2D::SetBuffer(Int_t buffersize, Option_t *)
{
// set the buffer size in units of 8 bytes (double)

   if (fBuffer) {
      BufferEmpty();
      delete [] fBuffer;
      fBuffer = 0;
   }
   if (buffersize <= 0) {
      fBufferSize = 0;
      return;
   }
   if (buffersize < 100) buffersize = 100;
   fBufferSize = 1 + 4*buffersize;
   fBuffer = new Double_t[fBufferSize];
   memset(fBuffer,0,8*fBufferSize);
}

//______________________________________________________________________________
void TProfile2D::SetErrorOption(Option_t *option)
{
//*-*-*-*-*-*-*-*-*-*Set option to compute profile2D errors*-*-*-*-*-*-*-*
//*-*                =======================================
//
//    The computation of errors is based on the parameter option:
//    option:
//     ' '  (Default) Errors are Spread/SQRT(N) for Spread.ne.0. ,
//                      "     "  SQRT(Z)/SQRT(N) for Spread.eq.0,N.gt.0 ,
//                      "     "  0.  for N.eq.0
//     's'            Errors are Spread  for Spread.ne.0. ,
//                      "     "  SQRT(Z)  for Spread.eq.0,N.gt.0 ,
//                      "     "  0.  for N.eq.0
//     'i'            Errors are Spread/SQRT(N) for Spread.ne.0. ,
//                      "     "  1./SQRT(12.*N) for Spread.eq.0,N.gt.0 ,
//                      "     "  0.  for N.eq.0
//   See TProfile2D::BuildOptions for explanation of all options

   TString opt = option;
   opt.ToLower();
   fErrorMode = kERRORMEAN;
   if (opt.Contains("s")) fErrorMode = kERRORSPREAD;
   if (opt.Contains("i")) fErrorMode = kERRORSPREADI;
   if (opt.Contains("g")) fErrorMode = kERRORSPREADG;
}

//______________________________________________________________________________
void TProfile2D::Streamer(TBuffer &R__b)
{
   // Stream an object of class TProfile2D.

   if (R__b.IsReading()) {
      UInt_t R__s, R__c;
      Version_t R__v = R__b.ReadVersion(&R__s, &R__c);
      if (R__v > 2) {
         TProfile2D::Class()->ReadBuffer(R__b, this, R__v, R__s, R__c);
         return;
      }
      //====process old versions before automatic schema evolution
      TH2D::Streamer(R__b);
      fBinEntries.Streamer(R__b);
      R__b >> (Int_t&)fErrorMode;
      if (R__v < 2) {
         Float_t zmin,zmax;
         R__b >> zmin; fZmin = zmin;
         R__b >> zmax; fZmax = zmax;
      } else {
         R__b >> fZmin;
         R__b >> fZmax;
      }
      R__b.CheckByteCount(R__s, R__c, TProfile2D::IsA());
      //====end of old versions

   } else {
      TProfile2D::Class()->WriteBuffer(R__b,this);
   }
}
