CombinedMinimumBuilder.cxx

Go to the documentation of this file.

// @(#)root/minuit2:$Id$
// Authors: M. Winkler, F. James, L. Moneta, A. Zsenei   2003-2005
 
/**********************************************************************
 *                                                                    *
 * Copyright (c) 2005 LCG ROOT Math team,  CERN/PH-SFT                *
 *                                                                    *
 **********************************************************************/
 
#include "Minuit2/AnalyticalGradientCalculator.h"
#include "Minuit2/CombinedMinimumBuilder.h"
#include "Minuit2/FunctionMinimum.h"
#include "Minuit2/MnStrategy.h"
#include "Minuit2/MnPrint.h"
 
namespace ROOT {
 
namespace Minuit2 {
 
FunctionMinimum CombinedMinimumBuilder::Minimum(const MnFcn &fcn, const GradientCalculator &gc, const MinimumSeed &seed,
                                                const MnStrategy &strategy, unsigned int maxfcn, double edmval) const
{
   // find minimum using combined method
   // (Migrad then if fails try Simplex and then Migrad again)
 
   MnPrint print("CombinedMinimumBuilder");
 
   FunctionMinimum min = fVMMinimizer.Builder().Minimum(fcn, gc, seed, strategy, maxfcn, edmval);
 
   if (!min.IsValid()) {
      print.Warn("Migrad method fails, will try with simplex method first");
 
      MnStrategy str(2);
      FunctionMinimum min1 = fSimplexMinimizer.Builder().Minimum(fcn, gc, seed, str, maxfcn, edmval);
      if (!min1.IsValid()) {
         print.Warn("Both Migrad and Simplex methods failed");
 
         return min1;
      }
      // check if gradient calculator is analytical
      auto agc = dynamic_cast<const AnalyticalGradientCalculator *>(&gc);
      MinimumSeed seed1 = (agc) ?
         fVMMinimizer.SeedGenerator()(fcn, *agc, min1.UserState(), str) : fVMMinimizer.SeedGenerator()(fcn, gc, min1.UserState(), str);
 
      FunctionMinimum min2 = fVMMinimizer.Builder().Minimum(fcn, gc, seed1, str, maxfcn, edmval);
      if (!min2.IsValid()) {
 
         print.Warn("Both migrad and method failed also at 2nd attempt; return simplex Minimum");
         return min1;
      }
 
      return min2;
   }
 
   return min;
}
 
} // namespace Minuit2
 
} // namespace ROOT