/data/refman/pasoursint/CMSSW_5_3_10_patch2/src/HiggsAnalysis/CombinedLimit/src/FeldmanCousins.cc

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#include <stdexcept>
#include "../interface/FeldmanCousins.h"
#include "../interface/Combine.h"
#include <RooRealVar.h>
#include <RooArgSet.h>
#include <RooArgSet.h>
#include <RooWorkspace.h>
#include <RooDataHist.h>
#include <RooStats/ModelConfig.h>
#include <RooStats/FeldmanCousins.h>
#include <RooStats/PointSetInterval.h>

float FeldmanCousins::toysFactor_ = 1;
float FeldmanCousins::rAbsAccuracy_ = 0.1;
float FeldmanCousins::rRelAccuracy_ = 0.02;

FeldmanCousins::FeldmanCousins() :
    LimitAlgo("FeldmanCousins specific options") {
    options_.add_options()
        ("rAbsAcc", boost::program_options::value<float>(&rAbsAccuracy_)->default_value(rAbsAccuracy_), "Absolute accuracy on r to reach to terminate the scan")
        ("rRelAcc", boost::program_options::value<float>(&rRelAccuracy_)->default_value(rRelAccuracy_), "Relative accuracy on r to reach to terminate the scan")
        ("toysFactor", boost::program_options::value<float>(&toysFactor_)->default_value(toysFactor_),   "Increase the toys per point by this factor w.r.t. the minimum from adaptive sampling")
    ;
}

void FeldmanCousins::applyOptions(const boost::program_options::variables_map &vm) 
{
}

bool FeldmanCousins::run(RooWorkspace *w, RooStats::ModelConfig *mc_s, RooStats::ModelConfig *mc_b, RooAbsData &data, double &limit, double &limitErr, const double *hint) {
  RooArgSet  poi(*mc_s->GetParametersOfInterest());
  RooRealVar *r = dynamic_cast<RooRealVar *>(poi.first());

  if ((hint != 0) && (*hint > r->getMin())) {
    r->setMax(std::min<double>(3*(*hint), r->getMax()));
  }

  RooStats::ModelConfig modelConfig(*mc_s);
  modelConfig.SetSnapshot(poi);

  RooStats::FeldmanCousins fc(data, modelConfig);
  fc.FluctuateNumDataEntries(mc_s->GetPdf()->canBeExtended());
  fc.UseAdaptiveSampling(true);
  fc.SetConfidenceLevel(cl);
  fc.AdditionalNToysFactor(toysFactor_);

  fc.SetNBins(10);
  do { 
      if (verbose > 1) std::cout << "scan in range [" << r->getMin() << ", " << r->getMax() << "]" << std::endl;
      std::auto_ptr<RooStats::PointSetInterval> fcInterval((RooStats::PointSetInterval *)fc.GetInterval());
      if (fcInterval.get() == 0) return false;
      if (verbose > 1) fcInterval->GetParameterPoints()->Print("V"); 
      RooDataHist* parameterScan = (RooDataHist*) fc.GetPointsToScan();
      int found = -1; 
      if (lowerLimit_) {
          for(int i=0; i<parameterScan->numEntries(); ++i){
              const RooArgSet * tmpPoint = parameterScan->get(i);
              if (!fcInterval->IsInInterval(*tmpPoint)) found = i;
              else break;
          }
      } else {
          for(int i=0; i<parameterScan->numEntries(); ++i){
              const RooArgSet * tmpPoint = parameterScan->get(i);
              bool inside = fcInterval->IsInInterval(*tmpPoint);
              if (inside) found = i;
              else if (found != -1) break;
          }
          if (found == -1) {
            if (verbose) std::cout << "Points are either all inside or all outside the bound." << std::endl;
            return false;
          }
      }
      double fcBefore = (found > -1 ? parameterScan->get(found)->getRealValue(r->GetName()) : r->getMin());
      double fcAfter  = (found < parameterScan->numEntries()-1 ? 
              parameterScan->get(found+1)->getRealValue(r->GetName()) : r->getMax());
      limit = 0.5*(fcAfter+fcBefore);
      limitErr = 0.5*(fcAfter-fcBefore);
      if (verbose > 0) std::cout << "  would be " << r->GetName() << " < " << limit << " +/- "<<limitErr << std::endl;
      r->setMin(std::max(r->getMin(), limit-3*limitErr)); 
      r->setMax(std::min(r->getMax(), limit+3*limitErr));
      if (limitErr < 4*std::max<float>(rAbsAccuracy_, rRelAccuracy_ * limit)) { // make last scan more precise
          fc.AdditionalNToysFactor(4*toysFactor_);
      }
  } while (limitErr > std::max<float>(rAbsAccuracy_, rRelAccuracy_ * limit));

  if (verbose > -1) {
      std::cout << "\n -- FeldmanCousins++ -- \n";
      std::cout << "Limit: " << r->GetName() << (lowerLimit_ ? "> " : "< ") << limit << " +/- " << limitErr << " @ " << cl * 100 << "% CL" << std::endl;
  }
  return true;
}