/* University College London dept of P&A course in C++ 3C59 
| all rights reserved 1999 
|
| Example:  Compton Analysis
|
| "Example of a simple C++ function to calculate inverse energy"
|
| Author: P.Clarke 
*/

#include <iostream>
#include <cmath>

//-----------------------
//Set constant values in define statements
#define EZERO 10 


//-----------------------
//Function to return inverse energy of Comptom scattered electron

float inverseScatteredEnergy( float phi ) 

{

  //Declare constants in the formula
  float eZero = EZERO ;

  //Scattered energy
  float scatteredEnergy ;

  //Calculate 
  scatteredEnergy = eZero / 2. / ( 1. - cos(phi) ) ;

  //Go home
  return scatteredEnergy ;

}



//--------------------------------------------------------
// Main program to use it

int main()
{

  // declare some variables
  float escatt ;
  float angle  ;
 
  // Set the angle (in radians) and call the function

  angle = 0.5 ;

  escatt = inverseScatteredEnergy( angle ) ;

  std::cout << " The scattered energy was " << escatt << std::endl ;

  // Do same again with different variable names to emphasise that
  // these have nothing to do with the names used to write the function

  float escatt2 ;
  float angle2 ;

  angle2 = 0.2 ;

  escatt2 = inverseScatteredEnergy( angle2 ) ;

  std::cout << " The second scattered energy was " << escatt2 << std::endl ;

  return 1 ;
}