#include "fstream"
#include "iostream"
#include "stdio.h"
#include "string.h"
#include "stdlib.h"
#include "TGraphErrors.h"
#include "TH2F.h"
#include "TCanvas.h"
#include "TF1.h"
#include "math.h"
#include "TMultiGraph.h"
#include "TMinuit.h"

using namespace std;


Double_t afunc(Double_t *x, Double_t *par){
  
  Float_t fitval = 0;
  
  fitval = (par[0] + par[1]*sin(x[0]));
  
  return (fitval);

}


void testfit(){

  const int bins = 12;

  double phi[bins] = {0.27, 0.77, 1.29, 1.81, 2.34, 2.90, 3.39, 3.89, 4.47, 4.99, 5.50, 6.00} ;
  double asym[bins] = {0.014, 0.027, 0.012, 0.030, 0.035, 0.005, -0.008, -0.038, -0.050, -0.021, -0.021, -0.014 } ;
  double asym_err[bins] = {0.00653693, 0.00587808, 0.00726165, 0.00876149,  0.0107372, 0.00865679, 0.0077391, 0.010013, 0.00988164, 0.00703232, 0.00586795, 0.00651871} ;
  double null[bins] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0};
  

  TGraphErrors *gr1 = new TGraphErrors(bins, phi, asym, null, asym_err);

  // Draw Graph
  gr1->Draw("AP");


  TF1 *gr_fit = new TF1("gr_fit", afunc, 0.0, 6.28, 2);
  
  gr_fit->SetParName(0, "Constant");
  gr_fit->SetParName(1, "sin #phi moment");
    
  gr_fit->SetParameter(0, 0.0);
  gr_fit->SetParameter(1, 0.02);
    
  gr_fit->SetParLimits(0, -.1, .1);
  gr_fit->SetParLimits(1, -0.2, 0.2);

    
  gr1->Fit(gr_fit, "RV");
  gr_fit->Draw("same");
    

}