An other way of drawing errors for 2D histograms

This example shows how to define a new histogram representation with a COMIS routine.

The routine derr.f
      Subroutine Derr(Id)
      Character*80 Chtitl
      Real Errx(2)
      Real Erry(2)
      Real Errz(2)
1     Call Hgive(Id,Chtitl,Nx,Xmin,Xmax,Ny,Ymin,Ymax,Nwt,Idb)                                  
      If (Ny.Eq.0) Return
      Zmin = Hcxy(1,1,1)
      Zmax = Zmin
2     Do i=1,Nx                                                                                
         Do j=1,Ny
            Z   = Hcxy(i,j,1)
            E   = Hcxy(i,j,2)
            Ze1 = Z-E
            Ze2 = Z+E
            If (Ze1.Lt.Zmin) Zmin=Ze1
            If (Ze1.Gt.Zmax) Zmax=Ze1
            If (Ze2.Lt.Zmin) Zmin=Ze2
            If (Ze2.Gt.Zmax) Zmax=Ze2
         Enddo
      Enddo
3     Call Hplfr3(Xmin,Xmax,Ymin,Ymax,Zmin,Zmax,30.,30.,'FWB')                                 
      Dx = (Xmax-Xmin)/Nx
      Dy = (Ymax-Ymin)/Ny
      X  = Xmin+Dx/2.
4     Do i=1,Nx                                                                                
         Y = Ymin+Dy/2.
         Do j=1,Ny
            Z       = Hcxy(i,j,1)
            E       = Hcxy(i,j,2)
            Errx(1) = X
            Errx(2) = Errx(1)
            Erry(1) = Y
            Erry(2) = Erry(1)
            Errz(1) = Z-E
            Errz(2) = Z+E
            Call Ipm3(1,X,Y,Z)
            Call Ipl3(2,Errx,Erry,Errz)
            Y = Y+Dy
         Enddo
         X = X+Dx
      Enddo
      End

How to use derr.f
      hi/file 0 pawhists.hbook
      hrin *
5     SET MTYP 20                                                                              
5     CALL DERR.F(200)

Retrieve informations about the histogram.
Loop over all the bins to find the minimum and the maximum taking care of the errors.
Draw the 3D frame.
Loop over all the bins and draw the error bars.
Set the marker type and invoke the derr routine.

			PAW Tutorial	Last update: 1999/04/01 14.58	Olivier.Couet@Cern.Ch