Inheritance diagram for CTPPSProtonReconstructionPlotter:

Classes
struct	ArmCorrelationPlots

struct	MultiRPPlots

struct	SingleMultiCorrelationPlots

struct	SingleRPPlots

Public Member Functions
	CTPPSProtonReconstructionPlotter (const edm::ParameterSet &)

	~CTPPSProtonReconstructionPlotter () override

Public Member Functions inherited from edm::one::EDAnalyzer<>
	EDAnalyzer ()=default

SerialTaskQueue *	globalLuminosityBlocksQueue () final

SerialTaskQueue *	globalRunsQueue () final

bool	wantsGlobalLuminosityBlocks () const final

bool	wantsGlobalRuns () const final

Public Member Functions inherited from edm::one::EDAnalyzerBase
void	callWhenNewProductsRegistered (std::function< void(BranchDescription const &)> const &func)

	EDAnalyzerBase ()

ModuleDescription const &	moduleDescription () const

bool	wantsStreamLuminosityBlocks () const

bool	wantsStreamRuns () const

	~EDAnalyzerBase () override

Public Member Functions inherited from edm::EDConsumerBase
std::vector< ConsumesInfo >	consumesInfo () const

void	convertCurrentProcessAlias (std::string const &processName)
	Convert "@currentProcess" in InputTag process names to the actual current process name. More...

	EDConsumerBase ()

	EDConsumerBase (EDConsumerBase const &)=delete

	EDConsumerBase (EDConsumerBase &&)=default

ESProxyIndex const *	esGetTokenIndices (edm::Transition iTrans) const

ProductResolverIndexAndSkipBit	indexFrom (EDGetToken, BranchType, TypeID const &) const

void	itemsMayGet (BranchType, std::vector< ProductResolverIndexAndSkipBit > &) const

void	itemsToGet (BranchType, std::vector< ProductResolverIndexAndSkipBit > &) const

std::vector< ProductResolverIndexAndSkipBit > const &	itemsToGetFrom (BranchType iType) const

void	labelsForToken (EDGetToken iToken, Labels &oLabels) const

void	modulesWhoseProductsAreConsumed (std::vector< ModuleDescription const * > &modules, ProductRegistry const &preg, std::map< std::string, ModuleDescription const * > const &labelsToDesc, std::string const &processName) const

EDConsumerBase const &	operator= (EDConsumerBase const &)=delete

EDConsumerBase &	operator= (EDConsumerBase &&)=default

bool	registeredToConsume (ProductResolverIndex, bool, BranchType) const

bool	registeredToConsumeMany (TypeID const &, BranchType) const

ProductResolverIndexAndSkipBit	uncheckedIndexFrom (EDGetToken) const

void	updateLookup (BranchType iBranchType, ProductResolverIndexHelper const &, bool iPrefetchMayGet)

void	updateLookup (eventsetup::ESRecordsToProxyIndices const &)

virtual	~EDConsumerBase () noexcept(false)

Private Member Functions
void	analyze (const edm::Event &, const edm::EventSetup &) override

void	CalculateTimingTrackingDistance (const reco::ForwardProton &proton, const CTPPSLocalTrackLite &tr, const CTPPSGeometry &geometry, double &de_x, double &de_x_unc)

void	endJob () override

Static Private Member Functions
static void	profileToRMSGraph (TProfile p, TGraphErrors g)

Private Attributes
std::map< unsigned int, ArmCorrelationPlots >	armCorrelationPlots_

signed int	maxNonEmptyEvents_

std::map< unsigned int, MultiRPPlots >	multiRPPlots_

signed int	n_non_empty_events_

std::string	outputFile_

std::unique_ptr< TProfile >	p_x_L_diffNF_vs_x_L_N_

std::unique_ptr< TProfile >	p_x_R_diffNF_vs_x_R_N_

std::unique_ptr< TProfile >	p_y_L_diffNF_vs_y_L_N_

std::unique_ptr< TProfile >	p_y_R_diffNF_vs_y_R_N_

unsigned int	rpId_45_F_

unsigned int	rpId_45_N_

unsigned int	rpId_56_F_

unsigned int	rpId_56_N_

std::map< unsigned int, SingleMultiCorrelationPlots >	singleMultiCorrelationPlots_

std::map< unsigned int, SingleRPPlots >	singleRPPlots_

edm::EDGetTokenT< reco::ForwardProtonCollection >	tokenRecoProtonsMultiRP_

edm::EDGetTokenT< reco::ForwardProtonCollection >	tokenRecoProtonsSingleRP_

edm::EDGetTokenT< CTPPSLocalTrackLiteCollection >	tokenTracks_

Additional Inherited Members
Public Types inherited from edm::one::EDAnalyzerBase
typedef EDAnalyzerBase	ModuleType

Public Types inherited from edm::EDConsumerBase
typedef ProductLabels	Labels

Static Public Member Functions inherited from edm::one::EDAnalyzerBase
static const std::string &	baseType ()

static void	fillDescriptions (ConfigurationDescriptions &descriptions)

static void	prevalidate (ConfigurationDescriptions &descriptions)

Protected Member Functions inherited from edm::EDConsumerBase
template<typename ProductType , BranchType B = InEvent>
EDGetTokenT< ProductType >	consumes (edm::InputTag const &tag)

EDGetToken	consumes (const TypeToGet &id, edm::InputTag const &tag)

template<BranchType B>
EDGetToken	consumes (TypeToGet const &id, edm::InputTag const &tag)

ConsumesCollector	consumesCollector ()
	Use a ConsumesCollector to gather consumes information from helper functions. More...

template<typename ProductType , BranchType B = InEvent>
void	consumesMany ()

void	consumesMany (const TypeToGet &id)

template<BranchType B>
void	consumesMany (const TypeToGet &id)

template<typename ESProduct , typename ESRecord , Transition Tr = Transition::Event>
auto	esConsumes ()

template<typename ESProduct , typename ESRecord , Transition Tr = Transition::Event>
auto	esConsumes (ESInputTag const &tag)

template<typename ProductType , BranchType B = InEvent>
EDGetTokenT< ProductType >	mayConsume (edm::InputTag const &tag)

EDGetToken	mayConsume (const TypeToGet &id, edm::InputTag const &tag)

template<BranchType B>
EDGetToken	mayConsume (const TypeToGet &id, edm::InputTag const &tag)

Detailed Description

Definition at line 32 of file CTPPSProtonReconstructionPlotter.cc.

Constructor & Destructor Documentation

CTPPSProtonReconstructionPlotter::CTPPSProtonReconstructionPlotter ( const edm::ParameterSet & ps )

explicit

Definition at line 426 of file CTPPSProtonReconstructionPlotter.cc.

     : tokenTracks_(consumes<CTPPSLocalTrackLiteCollection>(ps.getParameter<edm::InputTag>("tagTracks"))),
       tokenRecoProtonsSingleRP_(
           consumes<reco::ForwardProtonCollection>(ps.getParameter<InputTag>("tagRecoProtonsSingleRP"))),
       tokenRecoProtonsMultiRP_(
           consumes<reco::ForwardProtonCollection>(ps.getParameter<InputTag>("tagRecoProtonsMultiRP"))),
 
       rpId_45_N_(ps.getParameter<unsigned int>("rpId_45_N")),
       rpId_45_F_(ps.getParameter<unsigned int>("rpId_45_F")),
       rpId_56_N_(ps.getParameter<unsigned int>("rpId_56_N")),
       rpId_56_F_(ps.getParameter<unsigned int>("rpId_56_F")),
 
       outputFile_(ps.getParameter<string>("outputFile")),
       maxNonEmptyEvents_(ps.getUntrackedParameter<signed int>("maxNonEmptyEvents", -1)),
 
       p_x_L_diffNF_vs_x_L_N_(new TProfile("p_x_L_diffNF_vs_x_L_N", ";x_{LN};x_{LF} - x_{LN}", 100, 0., +20.)),
       p_x_R_diffNF_vs_x_R_N_(new TProfile("p_x_R_diffNF_vs_x_R_N", ";x_{RN};x_{RF} - x_{RN}", 100, 0., +20.)),
 
       p_y_L_diffNF_vs_y_L_N_(new TProfile("p_y_L_diffNF_vs_y_L_N", ";y_{LN};y_{LF} - y_{LN}", 100, -20., +20.)),
       p_y_R_diffNF_vs_y_R_N_(new TProfile("p_y_R_diffNF_vs_y_R_N", ";y_{RN};y_{RF} - y_{RN}", 100, -20., +20.)),
 
       n_non_empty_events_(0) {}

CTPPSProtonReconstructionPlotter::~CTPPSProtonReconstructionPlotter ( )

inlineoverride

Definition at line 35 of file CTPPSProtonReconstructionPlotter.cc.

References analyze(), and endJob().

35 {}

Member Function Documentation

void CTPPSProtonReconstructionPlotter::analyze	(	const edm::Event &	event,
		const edm::EventSetup &	iSetup
	)

overrideprivate

Definition at line 476 of file CTPPSProtonReconstructionPlotter.cc.

References CTPPSDetId::arm(), armCorrelationPlots_, CalculateTimingTrackingDistance(), reco::ForwardProton::contributingLocalTracks(), alignCSCRings::de_x, Exception, edm::EventSetup::get(), CTPPSLocalTrackLite::getX(), CTPPSLocalTrackLite::getY(), training_settings::idx, maxNonEmptyEvents_, multiRPPlots_, n_non_empty_events_, p_x_L_diffNF_vs_x_L_N_, p_x_R_diffNF_vs_x_R_N_, p_y_L_diffNF_vs_y_L_N_, p_y_R_diffNF_vs_y_R_N_, year_2016_postTS2_cff::rpId, rpId_45_F_, rpId_45_N_, rpId_56_F_, rpId_56_N_, CTPPSDetId::sdTrackingPixel, CTPPSDetId::sdTrackingStrip, singleMultiCorrelationPlots_, singleRPPlots_, tokenRecoProtonsMultiRP_, tokenRecoProtonsSingleRP_, and tokenTracks_.

Referenced by ~CTPPSProtonReconstructionPlotter().

                                                                                                  {
   // get input
   edm::Handle<CTPPSLocalTrackLiteCollection> hTracks;
   event.getByToken(tokenTracks_, hTracks);
 
   Handle<reco::ForwardProtonCollection> hRecoProtonsSingleRP;
   event.getByToken(tokenRecoProtonsSingleRP_, hRecoProtonsSingleRP);
 
   Handle<reco::ForwardProtonCollection> hRecoProtonsMultiRP;
   event.getByToken(tokenRecoProtonsMultiRP_, hRecoProtonsMultiRP);
 
   if (!hRecoProtonsSingleRP->empty())
     n_non_empty_events_++;
 
   if (maxNonEmptyEvents_ > 0 && n_non_empty_events_ > maxNonEmptyEvents_)
     throw cms::Exception("CTPPSProtonReconstructionPlotter") << "Number of non empty events reached maximum.";
 
   // get conditions
   edm::ESHandle<CTPPSGeometry> hGeometry;
   iSetup.get<VeryForwardRealGeometryRecord>().get(hGeometry);
 
   // track plots
   const CTPPSLocalTrackLite *tr_L_N = nullptr;
   const CTPPSLocalTrackLite *tr_L_F = nullptr;
   const CTPPSLocalTrackLite *tr_R_N = nullptr;
   const CTPPSLocalTrackLite *tr_R_F = nullptr;
   std::map<unsigned int, unsigned int> armTrackCounter, armTimingTrackCounter;
 
   for (const auto &tr : *hTracks) {
     CTPPSDetId rpId(tr.getRPId());
     unsigned int decRPId = rpId.arm() * 100 + rpId.station() * 10 + rpId.rp();
 
     if (decRPId == rpId_45_N_)
       tr_L_N = &tr;
     if (decRPId == rpId_45_F_)
       tr_L_F = &tr;
     if (decRPId == rpId_56_N_)
       tr_R_N = &tr;
     if (decRPId == rpId_56_F_)
       tr_R_F = &tr;
 
     armTrackCounter[rpId.arm()]++;
 
     const bool trackerRP =
         (rpId.subdetId() == CTPPSDetId::sdTrackingStrip || rpId.subdetId() == CTPPSDetId::sdTrackingPixel);
     if (!trackerRP)
       armTimingTrackCounter[rpId.arm()]++;
   }
 
   if (tr_L_N && tr_L_F) {
     p_x_L_diffNF_vs_x_L_N_->Fill(tr_L_N->getX(), tr_L_F->getX() - tr_L_N->getX());
     p_y_L_diffNF_vs_y_L_N_->Fill(tr_L_N->getY(), tr_L_F->getY() - tr_L_N->getY());
   }
 
   if (tr_R_N && tr_R_F) {
     p_x_R_diffNF_vs_x_R_N_->Fill(tr_R_N->getX(), tr_R_F->getX() - tr_R_N->getX());
     p_y_R_diffNF_vs_y_R_N_->Fill(tr_R_N->getY(), tr_R_F->getY() - tr_R_N->getY());
   }
 
   // initialise multiplicity counters
   std::map<unsigned int, unsigned int> singleRPMultiplicity, multiRPMultiplicity;
   singleRPMultiplicity[rpId_45_N_] = singleRPMultiplicity[rpId_45_F_] = singleRPMultiplicity[rpId_56_N_] =
       singleRPMultiplicity[rpId_56_F_] = 0;
   multiRPMultiplicity[0] = multiRPMultiplicity[1] = 0;
 
   // make single-RP-reco plots
   for (const auto &proton : *hRecoProtonsSingleRP) {
     CTPPSDetId rpId((*proton.contributingLocalTracks().begin())->getRPId());
     unsigned int decRPId = rpId.arm() * 100 + rpId.station() * 10 + rpId.rp();
     singleRPPlots_[decRPId].fill(proton, armTrackCounter[rpId.arm()]);
 
     if (proton.validFit())
       singleRPMultiplicity[decRPId]++;
   }
 
   for (const auto it : singleRPMultiplicity)
     singleRPPlots_[it.first].h_multiplicity->Fill(it.second);
 
   // make multi-RP-reco plots
   for (const auto &proton : *hRecoProtonsMultiRP) {
     CTPPSDetId rpId((*proton.contributingLocalTracks().begin())->getRPId());
     unsigned int armId = rpId.arm();
     multiRPPlots_[armId].fill(proton, armTrackCounter[armId]);
 
     if (proton.validFit())
       multiRPMultiplicity[armId]++;
   }
 
   for (const auto it : multiRPMultiplicity) {
     const auto &pl = multiRPPlots_[it.first];
     pl.h_multiplicity->Fill(it.second);
     pl.h2_timing_tracks_vs_prot_mult->Fill(it.second, armTimingTrackCounter[it.first]);
   }
 
   // define "clean condition" for each arm
   map<unsigned int, bool> clCo;
   clCo[0] = (singleRPMultiplicity[rpId_45_N_] && singleRPMultiplicity[rpId_45_F_] && multiRPMultiplicity[0] == 1);
   clCo[1] = (singleRPMultiplicity[rpId_56_N_] && singleRPMultiplicity[rpId_56_F_] && multiRPMultiplicity[1] == 1);
 
   // plot distances between multi-RP protons and timing tracks in the same arm
   for (const auto &proton : *hRecoProtonsMultiRP) {
     if (!proton.validFit())
       continue;
 
     CTPPSDetId rpId_proton((*proton.contributingLocalTracks().begin())->getRPId());
     unsigned int armId = rpId_proton.arm();
     const auto &pl = multiRPPlots_[armId];
 
     for (const auto &tr : *hTracks) {
       CTPPSDetId rpId_tr(tr.getRPId());
       if (rpId_tr.arm() != armId)
         continue;
 
       const bool trackerRP =
           (rpId_tr.subdetId() == CTPPSDetId::sdTrackingStrip || rpId_tr.subdetId() == CTPPSDetId::sdTrackingPixel);
       if (trackerRP)
         continue;
 
       double de_x = 0., de_x_unc = 0.;
       CalculateTimingTrackingDistance(proton, tr, *hGeometry, de_x, de_x_unc);
 
       double rd = (de_x_unc > 0.) ? de_x / de_x_unc : -1E10;
 
       pl.h_de_x_timing_vs_tracking->Fill(de_x);
       pl.h_de_x_rel_timing_vs_tracking->Fill(rd);
       pl.h_de_x_match_timing_vs_tracking->Fill(fabs(de_x / de_x_unc) <= 1. ? 1. : 0.);
 
       if (clCo[armId]) {
         if (armTimingTrackCounter[armId] == 1)
           pl.h_de_x_rel_timing_vs_tracking_ClCo->Fill(rd);
       }
     }
   }
 
   // plot xy maps
   for (const auto &proton : *hRecoProtonsMultiRP) {
     if (!proton.validFit())
       continue;
 
     CTPPSDetId rpId((*proton.contributingLocalTracks().begin())->getRPId());
     unsigned int armId = rpId.arm();
     const auto &pl = multiRPPlots_[armId];
     const auto &nTimingTracks = armTimingTrackCounter[armId];
 
     if (!clCo[armId])
       continue;
 
     double x_ref = 0., y_ref = 0.;
     if (armId == 0) {
       x_ref = tr_L_N->getX();
       y_ref = tr_L_N->getY();
     }
     if (armId == 1) {
       x_ref = tr_R_N->getX();
       y_ref = tr_R_N->getY();
     }
 
     if (nTimingTracks == 0)
       pl.h2_y_vs_x_tt0_ClCo->Fill(x_ref, y_ref);
     if (nTimingTracks == 1)
       pl.h2_y_vs_x_tt1_ClCo->Fill(x_ref, y_ref);
     if (nTimingTracks > 1)
       pl.h2_y_vs_x_ttm_ClCo->Fill(x_ref, y_ref);
   }
 
   // make correlation plots
   for (const auto &proton_m : *hRecoProtonsMultiRP) {
     CTPPSDetId rpId_m((*proton_m.contributingLocalTracks().begin())->getRPId());
     unsigned int arm = rpId_m.arm();
 
     const reco::ForwardProton *p_s_N = nullptr, *p_s_F = nullptr;
 
     /*
     printf("multi-RP candidate: ");
     for (const auto &tr_m : proton_m.contributingLocalTracks())
       printf("%u, ", tr_m.key());
     printf("\n");
     */
 
     for (const auto &proton_s : *hRecoProtonsSingleRP) {
       // skip if source of single-RP reco not included in multi-RP reco
       const auto key_s = proton_s.contributingLocalTracks()[0].key();
       bool compatible = false;
       for (const auto &tr_m : proton_m.contributingLocalTracks()) {
         if (tr_m.key() == key_s) {
           compatible = true;
           break;
         }
       }
 
       //printf("    key_s = %u --> compatible = %u\n", key_s, compatible);
 
       if (!compatible)
         continue;
 
       // fill single-multi plots
       CTPPSDetId rpId_s((*proton_s.contributingLocalTracks().begin())->getRPId());
       const unsigned int idx = rpId_s.arm() * 1000 + rpId_s.station() * 100 + rpId_s.rp() * 10 + rpId_s.arm();
       singleMultiCorrelationPlots_[idx].fill(proton_s, proton_m);
 
       //printf("    arm_s = %u, arm_m = %u\n", rpId_s.arm(), arm);
 
       // select protons for arm-correlation plots
       const unsigned int rpDecId_s = rpId_s.arm() * 100 + rpId_s.station() * 10 + rpId_s.rp();
       if (rpDecId_s == rpId_45_N_ || rpDecId_s == rpId_56_N_)
         p_s_N = &proton_s;
       if (rpDecId_s == rpId_45_F_ || rpDecId_s == rpId_56_F_)
         p_s_F = &proton_s;
     }
 
     // fill arm-correlation plots
     if (p_s_N && p_s_F)
       armCorrelationPlots_[arm].fill(*p_s_N, *p_s_F, proton_m);
   }
 }

void CTPPSProtonReconstructionPlotter::CalculateTimingTrackingDistance	(	const reco::ForwardProton &	proton,
		const CTPPSLocalTrackLite &	tr,
		const CTPPSGeometry &	geometry,
		double &	de_x,
		double &	de_x_unc
	)

private

Definition at line 451 of file CTPPSProtonReconstructionPlotter.cc.

References edm::RefVector< C, T, F >::at(), reco::ForwardProton::contributingLocalTracks(), CTPPSLocalTrackLite::getRPId(), CTPPSGeometry::getRPTranslation(), CTPPSLocalTrackLite::getX(), CTPPSLocalTrackLite::getXUnc(), mathSSE::sqrt(), and z.

Referenced by analyze(), and profileToRMSGraph().

                                                                                          {
   // identify tracking-RP tracks
   const auto &tr_i = *proton.contributingLocalTracks().at(0);
   const auto &tr_j = *proton.contributingLocalTracks().at(1);
 
   const double z_i = geometry.getRPTranslation(tr_i.getRPId()).z();
   const double z_j = geometry.getRPTranslation(tr_j.getRPId()).z();
 
   // interpolation from tracking RPs
   const double z_ti = -geometry.getRPTranslation(tr_ti.getRPId()).z();  // the minus sign fixes a bug in the diamond geometry
   const double f_i = (z_ti - z_j) / (z_i - z_j), f_j = (z_i - z_ti) / (z_i - z_j);
   const double x_inter = f_i * tr_i.getX() + f_j * tr_j.getX();
   const double x_inter_unc_sq = f_i * f_i * tr_i.getXUnc() * tr_i.getXUnc() + f_j * f_j * tr_j.getXUnc() * tr_j.getXUnc();
 
   // save distance
   de_x = tr_ti.getX() - x_inter;
   de_x_unc = sqrt(tr_ti.getXUnc() * tr_ti.getXUnc() + x_inter_unc_sq);
 }

void CTPPSProtonReconstructionPlotter::endJob ( void )

overrideprivatevirtual

Reimplemented from edm::one::EDAnalyzerBase.

Definition at line 694 of file CTPPSProtonReconstructionPlotter.cc.

References armCorrelationPlots_, DEFINE_FWK_MODULE, multiRPPlots_, n_non_empty_events_, outputFile_, p_x_L_diffNF_vs_x_L_N_, p_x_R_diffNF_vs_x_R_N_, p_y_L_diffNF_vs_y_L_N_, p_y_R_diffNF_vs_y_R_N_, singleMultiCorrelationPlots_, and singleRPPlots_.

Referenced by ~CTPPSProtonReconstructionPlotter().

                                               {
   LogInfo("CTPPSProtonReconstructionPlotter") << "n_non_empty_events = " << n_non_empty_events_;
 
   auto f_out = std::make_unique<TFile>(outputFile_.c_str(), "recreate");
 
   p_x_L_diffNF_vs_x_L_N_->Write();
   p_x_R_diffNF_vs_x_R_N_->Write();
 
   p_y_L_diffNF_vs_y_L_N_->Write();
   p_y_R_diffNF_vs_y_R_N_->Write();
 
   TDirectory *d_singleRPPlots = f_out->mkdir("singleRPPlots");
   for (const auto &it : singleRPPlots_) {
     gDirectory = d_singleRPPlots->mkdir(Form("rp%u", it.first));
     it.second.write();
   }
 
   TDirectory *d_multiRPPlots = f_out->mkdir("multiRPPlots");
   for (const auto &it : multiRPPlots_) {
     gDirectory = d_multiRPPlots->mkdir(Form("arm%u", it.first));
     it.second.write();
   }
 
   TDirectory *d_singleMultiCorrelationPlots = f_out->mkdir("singleMultiCorrelationPlots");
   for (const auto &it : singleMultiCorrelationPlots_) {
     unsigned int si_rp = it.first / 10;
     unsigned int mu_arm = it.first % 10;
 
     gDirectory = d_singleMultiCorrelationPlots->mkdir(Form("si_rp%u_mu_arm%u", si_rp, mu_arm));
     it.second.write();
   }
 
   TDirectory *d_armCorrelationPlots = f_out->mkdir("armCorrelationPlots");
   for (const auto &it : armCorrelationPlots_) {
     gDirectory = d_armCorrelationPlots->mkdir(Form("arm%u", it.first));
     it.second.write();
   }
 }

static void CTPPSProtonReconstructionPlotter::profileToRMSGraph	(	TProfile *	p,
		TGraphErrors *	g
	)

inlinestaticprivate

Definition at line 53 of file CTPPSProtonReconstructionPlotter.cc.

References EnergyCorrector::c, CalculateTimingTrackingDistance(), alignCSCRings::de_x, training_settings::idx, N, and mathSSE::sqrt().

Referenced by CTPPSProtonReconstructionPlotter::MultiRPPlots::write().

                                                               {
     for (int bi = 1; bi <= p->GetNbinsX(); ++bi) {
       double c = p->GetBinCenter(bi);
 
       double N = p->GetBinEntries(bi);
       double Sy = p->GetBinContent(bi) * N;
       double Syy = p->GetSumw2()->At(bi);
 
       double si_sq = Syy / N - Sy * Sy / N / N;
       double si = (si_sq >= 0.) ? sqrt(si_sq) : 0.;
       double si_unc_sq = si_sq / 2. / N;  // Gaussian approximation
       double si_unc = (si_unc_sq >= 0.) ? sqrt(si_unc_sq) : 0.;
 
       int idx = g->GetN();
       g->SetPoint(idx, c, si);
       g->SetPointError(idx, 0., si_unc);
     }
   }