// example of simulated annealing
// travelling salesman problem
//
//
// minimize total distance when visiting a set of cities 
//
// function to minimize  
// dumped sine way with many local minima, but only one global minimum
// 
// run in ROOT with 
//  root> .x testSimAnnealing.C+

#include <cmath>
#include "Math/GSLSimAnMinimizer.h"
#include "Math/WrappedParamFunction.h"
#include "TF1.h"
#include "TArrow.h"

double EnergyFunction( const double * x, const double * = 0) { 
   double z = (x[0]  - 1.);
   return std::exp( - z * z ) * std::sin( 8. * x[0] );  
}

using namespace ROOT::Math; 

void testSimAnnealing() { 

   // create sim annealing class 

   GSLSimAnMinimizer siman; 
   WrappedParamFunction<> wf(EnergyFunction, 1); 
   siman.SetFunction(wf); 
   siman.SetVariable(0,"x",15.5,0.1);
   siman.SetPrintLevel(0);  // set to 1 if want to debug each iteration
   bool ok = siman.Minimize();
   if (!ok) return;

   // plot the function 
   //TF1 * f = new TF1("f",wf,-2,3,0);
   TF1 * f = new TF1("f",EnergyFunction,-2,3,0);
   f->Draw(); 

   double xmin = *(siman.X());
   double ymin = siman.MinValue();
   std::cout << " xmin = " << xmin << " function value = " << ymin << std::endl;
   
   
   // show minimum location
   TArrow * l = new TArrow(xmin, -1.,xmin, ymin ); 
   l->SetLineWidth(3);
   l->SetLineColor(kRed);
   l->Draw();

}