Util.h

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// @(#)root/mathcore:$Id: Util.h 26079 2008-11-05 09:40:15Z pcanal $
// Author: L. Moneta Tue Nov 14 15:44:38 2006

/**********************************************************************
 *                                                                    *
 * Copyright (c) 2006  LCG ROOT Math Team, CERN/PH-SFT                *
 *                                                                    *
 *                                                                    *
 **********************************************************************/

// Utility functions for all ROOT Math classes 

#ifndef ROOT_Math_Util
#define ROOT_Math_Util

#include <string> 
#include <sstream> 

#include <cmath>
#include <limits>

namespace ROOT { 

   namespace Math { 



/** 
   namespace defining Utility functions needed by mathcore 
*/ 
namespace Util { 

/**
   Utility function for conversion to strings
*/
template<class T>
std::string ToString(const T& val)
{
   std::ostringstream buf;
   buf << val;
   
   std::string ret = buf.str();
   return ret;
}


/// safe evaluation of log(x) with a protections against negative or zero argument to the log 
/// smooth linear extrapolation below function values smaller than  epsilon
/// (better than a simple cut-off)
inline double EvalLog(double x) { 
   // evaluate the log 
#ifdef __CINT__
   static const double epsilon = 2.*2.2250738585072014e-308;
#else
   static const double epsilon = 2.*std::numeric_limits<double>::min();
#endif
   if(x<= epsilon) 
      return x/epsilon + std::log(epsilon) - 1; 
   else      
      return std::log(x);
}
 
}  // end namespace Util


   } // end namespace Math

} // end namespace ROOT


#endif /* ROOT_Math_Util */

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