%%cpp -d

#include "Math/Minimizer.h"
#include "Math/Factory.h"
#include "Math/Functor.h"
#include "TRandom2.h"
#include "TError.h"
#include <iostream>

double RosenBrock(const double *xx )
{
  const double x = xx[0];
  const double y = xx[1];
  const double tmp1 = y-x*x;
  const double tmp2 = 1-x;
  return 100*tmp1*tmp1+tmp2*tmp2;
}

const char * minName = "Minuit2";
const char *algoName = "";
int randomSeed = -1;

ROOT::Math::Minimizer* minimum =
   ROOT::Math::Factory::CreateMinimizer(minName, algoName);
if (!minimum) {
   std::cerr << "Error: cannot create minimizer \"" << minName
             << "\". Maybe the required library was not built?" << std::endl;
   return 1;
}

minimum->SetMaxFunctionCalls(1000000); // for Minuit/Minuit2
minimum->SetMaxIterations(10000);  // for GSL
minimum->SetTolerance(0.001);
minimum->SetPrintLevel(1);

ROOT::Math::Functor f(&RosenBrock,2);
double step[2] = {0.01,0.01};

double variable[2] = { -1.,1.2};
if (randomSeed >= 0) {
   TRandom2 r(randomSeed);
   variable[0] = r.Uniform(-20,20);
   variable[1] = r.Uniform(-20,20);
}

minimum->SetFunction(f);

minimum->SetVariable(0,"x",variable[0], step[0]);
minimum->SetVariable(1,"y",variable[1], step[1]);

minimum->Minimize();

const double *xs = minimum->X();
std::cout << "Minimum: f(" << xs[0] << "," << xs[1] << "): "
          << minimum->MinValue()  << std::endl;

if ( minimum->MinValue()  < 1.E-4 )
   std::cout << "Minimizer " << minName << " - " << algoName
             << "   converged to the right minimum" << std::endl;
else {
   std::cout << "Minimizer " << minName << " - " << algoName
             << "   failed to converge !!!" << std::endl;
   Error("NumericalMinimization","fail to converge");
}

return 0;