Shift an exponential function on the x axis

[T_man]

Hello,

I am trying to plot the lifetime plot of muons (which is an exponential function), however it is not working as I am intended, so I just want to move the whole graph so it start at 2 instead of 0 on the X axis, but without changing the initial hight at x = 0, so here is what I have done

#include "TH2S.h"          
  4 #include "string.h"        
  5 #include "TBranch.h"       
  6 #include "math.h"          
  7 #include "stdio.h"         
  8 #include "TF1.h"           
  9                            
 10     //Double_t = x>2;      
 11                            
 12     double f(double x,double c){
 13     double y;              
 14     y = (10000/2.2*exp((-x+c)/2.2));
 15     return y;              
 16     }                      
 17                            
 18 void pulsetime(){                                    
 33     TF1* Pos1 = new TF1("Pos1","f(x,[2])",0,10);
 34     //TF1* Pos2 = new TF1("Pos2","f(x,[2])",0,10); This is not working as expected
                   
 38     Int_t csizex = 1000;   
 39     Int_t csizey = 700;    
 40     Int_t cposx = 10000;   
 41     Int_t cposy = 500;     
 42     TCanvas* can = new TCanvas("c","", cposx, cposy, csizex, csizey);
 43     can->Divide(1, 1);     
 44                            
 45     can->cd(1);            
 46     gPad->SetGridy();      
 47     gPad->SetGridx();      
 48                            
 49     Pos1->SetLineColor(1); 
 50     Pos2->SetLineColor(2);                                                                                                                                                                                                                                                    
  
 57     Pos1->Draw();    
 58     Pos2->Draw("same");
                         
 64 }

[OSchaile]

Hi,
3 observations:

• Pos1 and Pos2 are identical (apart from name)
• your function f has 2 parameters, you use 3: f(x,[2])
• you never SetParameters

Otto