testIntegration.cxx

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#include "Math/Integrator.h"
#include "Math/IntegratorMultiDim.h"
#include "Math/AllIntegrationTypes.h"
#include "Math/Functor.h"
#include "Math/GaussIntegrator.h"

#include <cmath>

const double ERRORLIMIT = 1E-3;


double f(double x) {
   return x;
}

double f2(const double * x) {
   return x[0] + x[1];
}

void printTestResult(std::ostream & os, const char * type, int status) {
   os << "Test of " << type  << "\t: \t";
   if (!status)       os << "OK" << std::endl;
   else               os << "FAILED";
   os << std::endl << std::endl;
}


int testIntegration1D() {

   const double RESULT = 0.5;
   int status = 0;


   ROOT::Math::Functor1D wf(&f);
   ROOT::Math::Integrator ig(ROOT::Math::IntegrationOneDim::kADAPTIVESINGULAR);
   ig.SetFunction(wf);
   double val = ig.Integral(0,1);
   std::cout << "GSL adaptive sing. integral result is \t" << val << std::endl;
   status += std::fabs(val-RESULT) > ERRORLIMIT;

   ROOT::Math::Integrator ig2(ROOT::Math::IntegrationOneDim::kNONADAPTIVE);
   ig2.SetFunction(wf);
   val = ig2.Integral(0,1);
   std::cout << "GSL non-adaptiveintegral result is    \t" << val << std::endl;
   status += std::fabs(val-RESULT) > ERRORLIMIT;

   ROOT::Math::Integrator ig3(wf, ROOT::Math::IntegrationOneDim::kADAPTIVE);
   val = ig3.Integral(0,1);
   std::cout << "GSL adaptive integral result is       \t" << val << std::endl;
   status += std::fabs(val-RESULT) > ERRORLIMIT;

   //ROOT::Math::GaussIntegrator ig4;
   ROOT::Math::Integrator ig4(ROOT::Math::IntegrationOneDim::kGAUSS);
   ig4.SetFunction(wf);
   val = ig4.Integral(0,1);
   std::cout << "Cernlib Gauss integral result is      \t" << val << std::endl;
   status += std::fabs(val-RESULT) > ERRORLIMIT;

   ROOT::Math::Integrator ig5(ROOT::Math::IntegrationOneDim::kLEGENDRE);
   ig5.SetFunction(wf);
   val = ig5.Integral(0,1);
   std::cout << "Gauss-Legendre integral result is     \t" << val << std::endl;
   status += std::fabs(val-RESULT) > ERRORLIMIT;

   printTestResult(std::cerr,"one-dimensional integration  ",status);
   return status;
}

int testIntegrationMultiDim() {

   const double RESULT = 1.0;
   int status = 0;

   ROOT::Math::Functor wf(&f2,2);
   double a[2] = {0,0};
   double b[2] = {1,1};

   ROOT::Math::IntegratorMultiDim ig(ROOT::Math::IntegrationMultiDim::kADAPTIVE);
   ig.SetFunction(wf);
   double val = ig.Integral(a,b);
   std::cout << "Cernlib Adaptive integral result is " << val << std::endl;
   status += std::fabs(val-RESULT) > ERRORLIMIT;

   ROOT::Math::IntegratorMultiDim ig2(ROOT::Math::IntegrationMultiDim::kVEGAS);
   ig2.SetFunction(wf);
   val = ig2.Integral(a,b);
   std::cout << "GSL VEGAS integral result is       " << val << std::endl;
   status += std::fabs(val-RESULT) > ERRORLIMIT;

   ROOT::Math::IntegratorMultiDim ig3(wf,ROOT::Math::IntegrationMultiDim::kPLAIN);
   val = ig3.Integral(a,b);
   std::cout << "GSL PLAIN  integral result is      " << val << std::endl;
   status += std::fabs(val-RESULT) > ERRORLIMIT;

   ROOT::Math::IntegratorMultiDim ig4(wf,ROOT::Math::IntegrationMultiDim::kMISER);
   val = ig4.Integral(a,b);
   std::cout << "GSL MISER integral result is       " << val << std::endl;
   status += std::fabs(val-RESULT) > ERRORLIMIT;

   printTestResult(std::cerr,"multi-dimensional integration",status);

   return status;
}

int  main() {
   int status = 0;

   status += testIntegration1D();
   status += testIntegrationMultiDim();

   return status;
}