//
// this program tests the computation of gamma-A cross sections from
// UPC cross sections for different classes of fwd neutrons
//

// c++ headers
#include <iostream>
#include <fstream>

////////////////////////////////////////////////////////////////////////////////////////////

void UPC_XS(Double_t prob_1_0n0n, Double_t prob_1_Xn0n, Double_t prob_1_XnXn,
	    Double_t prob_2_0n0n, Double_t prob_2_Xn0n, Double_t prob_2_XnXn,
	    Double_t flux_1, Double_t flux_2, Double_t xs_1, Double_t xs_2)
// in this case, one gives the fluxes, probabilities of neutrons classes
// and gA cross sections at both rapidities (denoted by 1 and 2 here) to
// obtain the UPC cross sections
// NOTE: flux_2 corresponds to the higher WgA
// NOTE: Xn0n stands for (Xn0n+0nXn)
{
  // check probs
  Double_t prob_1 = prob_1_0n0n+prob_1_Xn0n+prob_1_XnXn;
  Double_t prob_2 = prob_2_0n0n+prob_2_Xn0n+prob_2_XnXn;

  cout << endl << "   tot prob_1 = " << prob_1 << " ... tot prob_2 = " << prob_2 << endl;

  // compute UPC cross sections
  Double_t UPC_XS_0n0n = flux_1*prob_1_0n0n*xs_1+flux_2*prob_2_0n0n*xs_2;
  Double_t UPC_XS_Xn0n = flux_1*prob_1_Xn0n*xs_1+flux_2*prob_2_Xn0n*xs_2;  
  Double_t UPC_XS_XnXn = flux_1*prob_1_XnXn*xs_1+flux_2*prob_2_XnXn*xs_2;

  // print out
  cout << "   UPC XSs: " << endl;
  cout << "     total = " << (UPC_XS_0n0n+UPC_XS_Xn0n+UPC_XS_XnXn) << endl;
  cout << "     0n0n = " << UPC_XS_0n0n  << endl;
  cout << "     Xn0n = " << UPC_XS_Xn0n  << endl;
  cout << "     XnXn = " << UPC_XS_XnXn  << endl << endl;;  
}


////////////////////////////////////////////////////////////////////////////////////////////

void Test_UPC_XS()
{
  // data for xs and flux from Michal Krelina (hs-model for rho)
  // data for probabilities from Michal Broz

  cout << " Computing case y = <-4.0,-2.5> " << endl;
  UPC_XS(0.894622,0.0809586,0.0243349,0.625904,0.279219,0.0940511,
  163.916,13.8525,0.0128431,0.0512776);
 

}