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	diff --git a/input_jets b/input_jets
	index a3bdfda..1ca770d 100644
	--- a/input_jets
	+++ b/input_jets
	@@ -1,58 +1,58 @@
	# number of attempted resummation phase space points for each input event
	trials: 10

	min extparton pt: 30 # minimum transverse momentum of extremal partons

	resummation jets: # resummation jet properties
	min pt: 35 # minimum jet transverse momentum
	algorithm: antikt # jet algorithm
	R: 0.4 # jet R parameter

	fixed order jets: # properties of input jets
	min pt: 30
	# by default, algorithm and R are like for resummation jets

	# treatment of he various event classes
	# the supported settings are: reweight, keep, discard
	# non-FKL events cannot be reweighted
	FKL: reweight
	unordered: keep
	non-FKL: keep

	# scale settings similar to original HEJ
	#
	# Use combinations of max jet pperp, input scales, ht/2,
	# and the jet invariant mass and vary all scales by factors
	# of 1, sqrt(2), and 2. Discard combinations where mur and muf
	# differ by a factor of more than two.
	#
	# The weight entries in the final events are ordered as follows:
	# 0-18: max jet pperp
	# 19-37: input scales
	# 38-56: ht/2
	# 57-75: jet invariant mass
	# In each of these groups, the first entry corresponds to the basic
	# scale choice. In the following entries, mur and muf are varied with
	# the above factors. The entries are ordered lexicographically so that
	# mur1 < mur2 or (mur1 == mur2 and muf1 < muf2).
	#
	# Note that in contrast to HEJ, the central choice for the event is always
	# max jet pperp and cannot be configured (yet).
	#
	# scales: [max jet pperp, input, Ht/2, jet invariant mass]
	# scale factors: [0.5, 0.7071, 1, 1.41421, 2]
	# max scale ratio: 2.0001

	scales: input

	log correction: false # whether or not to include higher order logs
	unweight: false # TODO: whether or not to unweight events

	Les Houches output: RHEJ.lhe

	#ROOT output: RHEJ.root
	histograms: all # TODO: histograms in ROOT output
	#histograms: [ydif, njets] # only save selected histograms

	#wtwt cut # optional cut on (event weight)^2
	-#RanLux init: ... # TODO: file for initialisation of random number engine
	+#RanLux init: ranlux.0 # file for initialisation of random number engine
	diff --git a/main.cc b/main.cc
	index f636f66..2056104 100644
	--- a/main.cc
	+++ b/main.cc
	@@ -1,151 +1,155 @@
	/**
	* Name: main.cc
	* Authors: Tuomas Hapola, Andreas Maier <andreas.maier@durham.ac.uk>
	*
	*/
	#include <fstream>
	#include <algorithm>
	#include <memory>
	#include <chrono>
	#include <iostream>

	#include "yaml-cpp/yaml.h"

	#include "LHEF.h"
	#include "src/LesHouchesWriter.hh"
	#include "src/Histograms.hpp"
	#include "Common.h"
	#include "src/EventReweighter.hh"
	#include "src/config.hh"
	#include "src/stream.hh"
	#include "src/ROOTWriter.hh"

	int event_number(std::string const & record){
	size_t start = record.rfind("Number of Events");
	start = record.find_first_of("123456789", start);
	if(start == std::string::npos) {
	throw std::invalid_argument("no event number record found");
	}
	const size_t end = record.find_first_not_of("0123456789", start);
	return std::stoi(record.substr(start, end - start));
	}

	RHEJ::Config load_config(char const * filename){
	try{
	return RHEJ::load_config(filename);
	}
	catch(std::exception const & exc){
	std::cerr << "Error: " << exc.what() << '\n';
	std::exit(EXIT_FAILURE);
	}
	}

	int main(int argn, char** argv) {
	using clock = std::chrono::system_clock;

	if (argn < 3) {
	std::cerr << "\n# Usage:\n./HEJ config_file input_file\n\n";
	return EXIT_FAILURE;
	}

	const auto start_time = clock::now();

	// read configuration
	const RHEJ::Config config = load_config(argv[1]);

	RHEJ::istream in{argv[2]};

	RHEJ::Histograms hist{
	config.resummation_jets.def, config.resummation_jets.min_pt
	};

	LHEF::Reader reader{in};

	//Les Houches output
	std::unique_ptr<RHEJ::LesHouchesWriter> writer;
	if(config.Les_Houches_output){
	writer = RHEJ::make_unique<RHEJ::LesHouchesWriter>(
	*config.Les_Houches_output, reader.heprup
	);
	}
	//ROOT output
	std::unique_ptr<RHEJ::ROOTWriter> root_writer;
	if(config.ROOT_output){
	constexpr double infinity = std::numeric_limits<double>::infinity();
	root_writer = RHEJ::make_unique<RHEJ::ROOTWriter>(
	*config.ROOT_output,
	config.resummation_jets.def, config.resummation_jets.min_pt,
	config.wtwt_cut?(*config.wtwt_cut):infinity
	);
	}

	double global_reweight = 1.;
	int max_events = std::numeric_limits<int>::max();
	if(argn > 3){
	max_events = std::stoi(argv[3]);
	const int input_events = event_number(reader.headerBlock);
	global_reweight = input_events/static_cast<double>(max_events);
	std::cout << "processing " << max_events
	<< " out of " << input_events << " events\n";
	}

	RHEJ::EventReweighter rhej{
	reader.heprup,
	config.resummation_jets.def, config.resummation_jets.min_pt,
	config.fixed_order_jets.def, config.fixed_order_jets.min_pt,
	config.treat,
	config.min_extparton_pt,
	config.log_correction
	};
	+ if(config.RanLux_init){
	+ RHEJ::PhaseSpacePoint::reset_ranlux(*config.RanLux_init);
	+ }
	+
	int nevent = 0;
	std::array<int, RHEJ::event_class::last_class + 1>
	nevent_class{0}, nfailed_class{0};

	// Loop over the events in the inputfile
	while(reader.readEvent()){
	// reweight events so that the total cross section is conserved
	reader.hepeup.setWeight(0, global_reweight * reader.hepeup.weight());

	if(nevent == max_events) break;
	nevent++;

	if (nevent % 10000 == 0)
	std::cout << "event number " << nevent << std::endl;

	// calculate rHEJ weight
	RHEJ::Event FO_event{reader.hepeup};
	std::vector<RHEJ::Event> resummed_events;
	resummed_events = rhej.reweight(FO_event, config.trials, config.scale_gen);
	const auto ev_class = rhej.last_event_class();
	++nevent_class[ev_class];

	if(resummed_events.empty()) ++nfailed_class[ev_class];

	for(auto const & ev: resummed_events){
	assert(ev.outgoing.size() >= 2);
	const double wt = ev.central.weight;

	if(config.wtwt_cut && wtwt > config.wtwt_cut){
	if(root_writer) root_writer->write(ev);
	continue;
	}

	if(config.ROOT_output) hist.fill(ev);

	if(config.Les_Houches_output) writer->write(ev);
	}
	} // main event loop

	if(root_writer) root_writer->write(hist);

	using namespace RHEJ::event_class;
	std::cout<< "Events processed: " << nevent << '\n';
	for(size_t ev_class = first_class; ev_class <= last_class; ++ev_class){
	std::cout << '\t' << names[ev_class] << ": " << nevent_class[ev_class]
	<< ", failed to reconstruct " << nfailed_class[ev_class]
	<< '\n';
	}

	std::chrono::duration<double> run_time = (clock::now() - start_time);
	std::cout << "\nTask Runtime: " << run_time.count() << " seconds.\n";
	}
	diff --git a/src/PhaseSpacePoint.cc b/src/PhaseSpacePoint.cc
	index 21a783b..c9ffc2b 100644
	--- a/src/PhaseSpacePoint.cc
	+++ b/src/PhaseSpacePoint.cc
	@@ -1,551 +1,560 @@
	#include "PhaseSpacePoint.hpp"

	#include <random>

	#include "src/FindObservedJetMomenta.h"
	#include "src/Jacobian.hpp"
	#include "src/RNGWrapper.hpp"
	#include "src/uno.hh"
	#include "src/debug.hpp"
	#include "src/kinematics.hh"

	namespace RHEJ{

	namespace{
	//generate Ranlux64Engine with fixed, predefined state
	/*
	* some (all?) of the Ranlux64Engine constructors leave fields
	* uninitialised, invoking undefined behaviour. This can be
	* circumvented by restoring the state from a file
	*/
	CLHEP::Ranlux64Engine gen_Ranlux64Engine(){
	static const std::string state =
	"9876\n"
	"0.91280703978419097666\n"
	"0.41606065829518357191\n"
	"0.99156342622341142601\n"
	"0.030922955274050423213\n"
	"0.16206278421638486975\n"
	"0.76151768001958330956\n"
	"0.43765760066092695979\n"
	"0.42904698253748563275\n"
	"0.11476317525663759511\n"
	"0.026620053590963976831\n"
	"0.65953715764414511114\n"
	"0.30136722624439826745\n"
	"3.5527136788005009294e-15 4\n"
	"1 202\n";
	const std::string file = std::tmpnam(nullptr);
	{
	std::ofstream out{file};
	out << state;
	}
	CLHEP::Ranlux64Engine result;
	result.restoreStatus(file.c_str());
	return result;
	}
	}

	CLHEP::Ranlux64Engine PhaseSpacePoint::ran_{gen_Ranlux64Engine()};

	+
	+ void PhaseSpacePoint::reset_ranlux(std::string const & init_file){
	+ reset_ranlux(init_file.c_str());
	+ }
	+
	+ void PhaseSpacePoint::reset_ranlux(char const * init_file){
	+ ran_.restoreStatus(init_file);
	+ }
	+
	namespace {
	constexpr int max_jet_user_idx = PhaseSpacePoint::ng_max;

	bool is_nonjet_parton(fastjet::PseudoJet const & parton){
	assert(parton.user_index() != -1);
	return parton.user_index() > max_jet_user_idx;
	}

	bool is_jet_parton(fastjet::PseudoJet const & parton){
	assert(parton.user_index() != -1);
	return parton.user_index() <= max_jet_user_idx;
	}

	// user indices for partons with extremal rapidity
	constexpr int y_min_user_idx = -3;
	constexpr int y_max_user_idx = -2;
	}

	namespace{
	double estimate_ng_mean(std::vector<fastjet::PseudoJet> const & Born_jets){
	const double delta_y =
	Born_jets.back().rapidity() - Born_jets.front().rapidity();
	assert(delta_y > 0);
	// Formula derived from fit to 2 jet data
	// for 3 jets: -0.0131111 + (1.39385 + 0.050085delta_y)delta_y
	return -0.0213569 + (1.39765 + 0.0498387delta_y)delta_y;
	}
	}

	std::vector<fastjet::PseudoJet> PhaseSpacePoint::cluster_jets(
	std::vector<fastjet::PseudoJet> const & partons
	) const{
	fastjet::ClusterSequence cs(partons, jet_def_);
	return cs.inclusive_jets(jetptmin_);
	}

	bool PhaseSpacePoint::pass_resummation_cuts(
	std::vector<fastjet::PseudoJet> const & jets
	) const{
	return cluster_jets(jets).size() == jets.size();
	}

	int PhaseSpacePoint::sample_ng(std::vector<fastjet::PseudoJet> const & Born_jets){
	const double ng_mean = estimate_ng_mean(Born_jets);
	std::poisson_distribution<int> dist(ng_mean);
	RNGWrapper<CLHEP::Ranlux64Engine> rng{ran_};
	const int ng = dist(rng);
	assert(ng >= 0);
	assert(ng < ng_max);
	weight_ = std::tgamma(ng + 1)std::exp(ng_mean)*std::pow(ng_mean, -ng);
	return ng;
	}

	namespace {
	void copy_AWZH_boson(
	std::vector<Sparticle> const & from,
	std::vector<Sparticle> & to
	){
	const auto AWZH_boson = std::find_if(
	begin(from), end(from),
	[](Sparticle const & p){ return is_AWZH_boson(p); }
	);
	if(AWZH_boson == end(from)) return;
	auto insertion_point = std::lower_bound(
	begin(to), end(to), *AWZH_boson, rapidity_less{}
	);
	to.insert(insertion_point, *AWZH_boson);
	assert(std::is_sorted(begin(to), end(to), rapidity_less{}));
	}
	}

	PhaseSpacePoint::PhaseSpacePoint(
	Event const & ev,
	fastjet::JetDefinition jet_def, double jetptmin,
	fastjet::JetDefinition Born_jet_def, double Born_jetptmin,
	double extpartonptmin
	):
	unob_{has_unob_gluon(ev.incoming, ev.outgoing)},
	unof_{!unob_ && has_unof_gluon(ev.incoming, ev.outgoing)},
	extpartonptmin_{extpartonptmin},
	jetptmin_{jetptmin},
	Born_jetptmin_{Born_jetptmin},
	jet_def_{jet_def},
	Born_jet_def_{Born_jet_def},
	splitter_{jet_def.R(), jet_def, jetptmin, ran_}
	{
	weight_ = 1;
	fastjet::ClusterSequence cs(
	to_PseudoJet(filter_partons(ev.outgoing)),
	Born_jet_def_
	);
	const auto Born_jets = sorted_by_rapidity(
	cs.inclusive_jets(Born_jetptmin_)
	);
	const int ng = sample_ng(Born_jets);
	weight_ /= std::tgamma(ng + 1);
	const int ng_jets = sample_ng_jets(ng, Born_jets);
	std::vector<fastjet::PseudoJet> out_partons = gen_non_jet(
	ng - ng_jets, ccut, jetptmin_
	);
	{
	const auto qperp = std::accumulate(
	begin(out_partons), end(out_partons),
	fastjet::PseudoJet{}
	);
	const auto jets = reshuffle(Born_jets, qperp);
	if(weight_ == 0.) return;
	if(! pass_resummation_cuts(jets)){
	weight_ = 0.;
	return;
	}
	std::vector<fastjet::PseudoJet> jet_partons = split(jets, ng_jets);
	if(weight_ == 0.) return;
	rescale_rapidities(
	out_partons,
	most_backward_FKL(jet_partons).rapidity(),
	most_forward_FKL(jet_partons).rapidity()
	);
	if(! cluster_jets(out_partons).empty()){
	weight_ = 0.;
	return;
	}
	std::sort(begin(out_partons), end(out_partons), rapidity_less{});
	assert(
	std::is_sorted(begin(jet_partons), end(jet_partons), rapidity_less{})
	);
	const auto first_jet_parton = out_partons.insert(
	end(out_partons), begin(jet_partons), end(jet_partons)
	);
	std::inplace_merge(
	begin(out_partons), first_jet_parton, end(out_partons), rapidity_less{}
	);
	assert(extremal_FKL_ok(out_partons));
	}
	if(! jets_ok(Born_jets, out_partons)){
	weight_ = 0.;
	return;
	}
	weight_ *= phase_space_normalisation(Born_jets.size(), out_partons.size());

	outgoing_.reserve(out_partons.size() + 1); // one slot for possible A, W, Z, H
	for(auto & p: out_partons){
	outgoing_.emplace_back(Sparticle{pid::gluon, std::move(p)});
	}
	most_backward_FKL(outgoing_).type = ev.incoming.front().type;
	most_forward_FKL(outgoing_).type = ev.incoming.back().type;
	copy_AWZH_boson(ev.outgoing, outgoing_);

	assert(!outgoing_.empty());
	reconstruct_incoming(ev.incoming);
	}

	std::vector<fastjet::PseudoJet> PhaseSpacePoint::gen_non_jet(
	int count, double ptmin, double ptmax
	){
	// heuristic parameters for pt sampling
	const double ptpar = 1.3 + count/5.;
	const double temp1 = atan((ptmax - ptmin)/ptpar);

	std::vector<fastjet::PseudoJet> partons(count);
	for(size_t i = 0; i < (size_t) count; ++i){
	const double r1 = ran_.flat();
	const double pt = ptmin + ptpartan(r1temp1);
	const double temp2 = cos(r1*temp1);
	const double phi = 2M_PIran_.flat();
	weight_ = 2.0M_PIptptpartemp1/(temp2temp2);
	// we don't know the allowed rapidity span yet,
	// set a random value to be rescaled later on
	const double y = ran_.flat();
	partons[i].reset_PtYPhiM(pt, y, phi);
	// Set user index higher than any jet-parton index
	// in order to assert that these are not inside jets
	partons[i].set_user_index(i + 1 + RHEJ::PhaseSpacePoint::ng_max);

	assert(ptmin-1e-5 <= partons[i].pt() && partons[i].pt() <= ptmax+1e-5);
	}
	assert(std::all_of(partons.cbegin(), partons.cend(), is_nonjet_parton));
	return partons;
	}

	void PhaseSpacePoint::rescale_rapidities(
	std::vector<fastjet::PseudoJet> & partons,
	double ymin, double ymax
	){
	constexpr double ep = 1e-7;
	for(auto & parton: partons){
	assert(0 <= parton.rapidity() && parton.rapidity() <= 1);
	const double dy = ymax - ymin - 2*ep;
	const double y = ymin + ep + dy*parton.rapidity();
	parton.reset_momentum_PtYPhiM(parton.pt(), y, parton.phi());
	weight_ *= dy;
	assert(ymin <= parton.rapidity() && parton.rapidity() <= ymax);
	}
	}

	double PhaseSpacePoint::probability_in_jet(
	std::vector<fastjet::PseudoJet> const & Born_jets
	) const{
	assert(std::is_sorted(begin(Born_jets), end(Born_jets), rapidity_less{}));
	assert(Born_jets.size() >= 2);

	const double dy =
	Born_jets.back().rapidity() - Born_jets.front().rapidity();
	const double R_eff = splitter_.R_factor*jet_def_.R();
	const int njets = Born_jets.size();
	const double p_J = (dy > 2.R_eff(njets-1))?
	(njets-1)R_effR_eff/(2.*dy):
	njetsR_effR_eff/(2.(dy + 2.R_eff));
	return std::min(p_J, 1.);
	}

	int PhaseSpacePoint::sample_ng_jets(
	int ng, std::vector<fastjet::PseudoJet> const & Born_jets
	){
	RNGWrapper<CLHEP::Ranlux64Engine> rng{ran_};
	const double p_J = probability_in_jet(Born_jets);
	std::binomial_distribution<> bin_dist(ng, p_J);
	const int ng_J = bin_dist(rng);
	weight_ = std::pow(p_J, -ng_J)std::pow(1 - p_J, ng_J - ng);
	return ng_J;
	}

	std::vector<fastjet::PseudoJet>
	PhaseSpacePoint::reshuffle(
	std::vector<fastjet::PseudoJet> const & Born_jets,
	fastjet::PseudoJet const & q
	){
	if(q == fastjet::PseudoJet{0, 0, 0, 0}) return Born_jets;
	std::vector<fastjet::PseudoJet> jets = FindJetMomenta(Born_jets, q);
	if(jets.empty()){
	weight_ = 0;
	return {};
	}
	// transform delta functions to integration over resummation momenta
	weight_ /= Jacobian(jets, q);
	return jets;
	}

	std::vector<int> PhaseSpacePoint::distribute_jet_partons(
	int ng_jets, std::vector<fastjet::PseudoJet> const & jets
	){
	size_t first_valid_jet = 0;
	size_t num_valid_jets = jets.size();
	const double R_eff = 5./3.*jet_def_.R();
	// if there is an unordered jet too far away from the FKL jets
	// then extra gluon constituents of the unordered jet would
	// violate the FKL rapidity ordering
	if(unob_ && jets[0].delta_R(jets[1]) > R_eff){
	++first_valid_jet;
	--num_valid_jets;
	}
	else if(unof_ && jets[jets.size()-1].delta_R(jets[jets.size()-2]) > R_eff){
	--num_valid_jets;
	}
	std::vector<int> np(jets.size(), 1);
	for(int i = 0; i < ng_jets; ++i){
	++np[first_valid_jet + ran_.flat() * num_valid_jets];
	}
	weight_ *= std::pow(num_valid_jets, ng_jets);
	return np;
	}

	#ifndef NDEBUG
	namespace{
	bool tagged_FKL_backward(
	std::vector<fastjet::PseudoJet> const & jet_partons
	){
	return std::find_if(
	begin(jet_partons), end(jet_partons),
	[](fastjet::PseudoJet const & p){
	return p.user_index() == y_min_user_idx;
	}
	) != end(jet_partons);
	}

	bool tagged_FKL_forward(
	std::vector<fastjet::PseudoJet> const & jet_partons
	){
	// the most forward FKL parton is most likely near the end of jet_partons;
	// start search from there
	return std::find_if(
	rbegin(jet_partons), rend(jet_partons),
	[](fastjet::PseudoJet const & p){
	return p.user_index() == y_min_user_idx;
	}
	) != rend(jet_partons);
	}

	bool tagged_FKL_extremal(
	std::vector<fastjet::PseudoJet> const & jet_partons
	){
	return tagged_FKL_backward(jet_partons) && tagged_FKL_forward(jet_partons);
	}

	} // end anonymous namespace
	#endif

	std::vector<fastjet::PseudoJet> PhaseSpacePoint::split(
	std::vector<fastjet::PseudoJet> const & jets,
	int ng_jets
	){
	return split(jets, distribute_jet_partons(ng_jets, jets));
	}

	std::vector<fastjet::PseudoJet> PhaseSpacePoint::split(
	std::vector<fastjet::PseudoJet> const & jets,
	std::vector<int> const & np
	){
	assert(! jets.empty());
	assert(jets.size() == np.size());
	assert(pass_resummation_cuts(jets));

	const size_t most_backward_FKL_idx = 0 + unob_;
	const size_t most_forward_FKL_idx = jets.size() - 1 - unof_;

	std::vector<fastjet::PseudoJet> jet_partons;
	// randomly distribute jet gluons among jets
	for(size_t i = 0; i < jets.size(); ++i){
	weight_ *= splitter_.Split(jets[i], np[i]);
	if(weight_ == 0) return {};
	assert(
	std::all_of(
	begin(splitter_.get_jcons()), end(splitter_.get_jcons()),
	is_jet_parton
	)
	);
	const auto first_new_parton = jet_partons.insert(
	end(jet_partons),
	begin(splitter_.get_jcons()), end(splitter_.get_jcons())
	);
	auto extremal = end(jet_partons);
	if((unob_ && i == 0) \|\| i == most_backward_FKL_idx){
	// unordered or FKL backward emission
	extremal = std::min_element(
	first_new_parton, end(jet_partons), rapidity_less{}
	);
	if(i == most_backward_FKL_idx) extremal->set_user_index(y_min_user_idx);
	}
	else if((unof_ && i == jets.size() - 1) \|\| i == most_forward_FKL_idx){
	// unordered or FKL forward emission
	extremal = std::max_element(
	first_new_parton, end(jet_partons), rapidity_less{}
	);
	if(i == most_forward_FKL_idx) extremal->set_user_index(y_max_user_idx);
	}
	if(extremal != end(jet_partons) && extremal->pt() < extpartonptmin_){
	weight_ = 0;
	return {};
	}
	}
	assert(tagged_FKL_extremal(jet_partons));
	std::sort(begin(jet_partons), end(jet_partons), rapidity_less{});
	if(
	!extremal_FKL_ok(jet_partons)
	\|\| !split_preserved_jets(jets, jet_partons)
	){
	weight_ = 0.;
	return {};
	}
	return jet_partons;
	}

	bool PhaseSpacePoint::extremal_FKL_ok(
	std::vector<fastjet::PseudoJet> const & partons
	) const{
	assert(std::is_sorted(begin(partons), end(partons), rapidity_less{}));
	return
	most_backward_FKL(partons).user_index() == y_min_user_idx
	&& most_forward_FKL(partons).user_index() == y_max_user_idx;
	}

	bool PhaseSpacePoint::split_preserved_jets(
	std::vector<fastjet::PseudoJet> const & jets,
	std::vector<fastjet::PseudoJet> const & jet_partons
	) const{
	assert(std::is_sorted(begin(jets), end(jets), rapidity_less{}));

	const auto split_jets = sorted_by_rapidity(cluster_jets(jet_partons));
	// this can happen if two overlapping jets
	// are both split into more than one parton
	if(split_jets.size() != jets.size()) return false;
	for(size_t i = 0; i < split_jets.size(); ++i){
	// this can happen if there are two overlapping jets
	// and a parton is assigned to the "wrong" jet
	if(!nearby_ep(jets[i].rapidity(), split_jets[i].rapidity(), 1e-2)){
	return false;
	}
	}
	return true;
	}

	template<class Particle>
	Particle const & PhaseSpacePoint::most_backward_FKL(
	std::vector<Particle> const & partons
	) const{
	return partons[0 + unob_];
	}

	template<class Particle>
	Particle const & PhaseSpacePoint::most_forward_FKL(
	std::vector<Particle> const & partons
	) const{
	const size_t idx = partons.size() - 1 - unof_;
	assert(idx < partons.size());
	return partons[idx];
	}

	template<class Particle>
	Particle & PhaseSpacePoint::most_backward_FKL(
	std::vector<Particle> & partons
	) const{
	return partons[0 + unob_];
	}

	template<class Particle>
	Particle & PhaseSpacePoint::most_forward_FKL(
	std::vector<Particle> & partons
	) const{
	const size_t idx = partons.size() - 1 - unof_;
	assert(idx < partons.size());
	return partons[idx];
	}

	namespace{
	bool contains_idx(
	fastjet::PseudoJet const & jet, fastjet::PseudoJet const & parton
	){
	auto const & constituents = jet.constituents();
	const int idx = parton.user_index();
	return std::find_if(
	begin(constituents), end(constituents),
	[idx](fastjet::PseudoJet const & con){return con.user_index() == idx;}
	) != end(constituents);
	}
	}

	/**
	* final jet test:
	* - number of jets must match Born kinematics
	* - no partons designated as nonjet may end up inside jets
	* - all other outgoing partons must end up inside jets
	* - the extremal (in rapidity) partons must be inside the extremal jets
	* - rapidities must be the same (by construction)
	*/
	bool PhaseSpacePoint::jets_ok(
	std::vector<fastjet::PseudoJet> const & Born_jets,
	std::vector<fastjet::PseudoJet> const & partons
	) const{
	fastjet::ClusterSequence cs(partons, jet_def_);
	const auto jets = sorted_by_rapidity(cs.inclusive_jets(jetptmin_));
	if(jets.size() != Born_jets.size()) return false;
	int in_jet = 0;
	for(size_t i = 0; i < jets.size(); ++i){
	assert(jets[i].has_constituents());
	for(auto && parton: jets[i].constituents()){
	if(is_nonjet_parton(parton)) return false;
	}
	in_jet += jets[i].constituents().size();
	}
	const int expect_in_jet = std::count_if(
	partons.cbegin(), partons.cend(), is_jet_parton
	);
	if(in_jet != expect_in_jet) return false;
	// note that PseudoJet::contains does not work here
	if(! (
	contains_idx(most_backward_FKL(jets), most_backward_FKL(partons))
	&& contains_idx(most_forward_FKL(jets), most_forward_FKL(partons))
	)) return false;
	for(size_t i = 0; i < jets.size(); ++i){
	assert(nearby_ep(jets[i].rapidity(), Born_jets[i].rapidity(), 1e-2));
	}
	return true;
	}

	namespace{
	}

	void PhaseSpacePoint::reconstruct_incoming(
	std::array<Sparticle, 2> const & Born_incoming
	){
	std::tie(incoming_[0].p, incoming_[1].p) = incoming_momenta(outgoing_);
	for(size_t i = 0; i < incoming_.size(); ++i){
	incoming_[i].type = Born_incoming[i].type;
	}
	assert(momentum_conserved(1e-7));
	}

	double PhaseSpacePoint::phase_space_normalisation(
	int num_Born_jets, int num_out_partons
	) const{
	return pow(16*pow(M_PI,3), num_Born_jets - num_out_partons);
	}

	bool PhaseSpacePoint::momentum_conserved(double ep) const{
	fastjet::PseudoJet diff;
	for(auto const & in: incoming()) diff += in.p;
	for(auto const & out: outgoing()) diff -= out.p;
	return nearby_ep(diff, fastjet::PseudoJet{}, ep);
	}

	}
	diff --git a/src/PhaseSpacePoint.hpp b/src/PhaseSpacePoint.hpp
	index 2f97d74..2b2b420 100644
	--- a/src/PhaseSpacePoint.hpp
	+++ b/src/PhaseSpacePoint.hpp
	@@ -1,121 +1,124 @@
	#pragma once

	#include <vector>

	#include <CLHEP/Random/Randomize.h>
	#include <CLHEP/Random/RanluxEngine.h>

	#include "Common.h"
	#include "Event.hh"
	#include "splitter.h"

	namespace RHEJ{

	// A point in resummation phase space
	class PhaseSpacePoint{
	public:
	PhaseSpacePoint() = default;

	PhaseSpacePoint(
	Event const & ev,
	fastjet::JetDefinition jet_def, double jetptmin,
	fastjet::JetDefinition Born_jet_def, double Born_jetptmin,
	double extpartonptmin
	);

	double weight() const{
	return weight_;
	}

	std::array<Sparticle, 2> const & incoming() const{
	return incoming_;
	}
	std::vector<Sparticle> const & outgoing() const{
	return outgoing_;
	}

	static constexpr double ccut = 0.2; // universal min pt cut
	static constexpr int ng_max = 1000; // maximum number of extra gluons

	+ static void reset_ranlux(std::string const & init_file);
	+ static void reset_ranlux(char const * init_file);
	+
	private:

	std::vector<fastjet::PseudoJet> cluster_jets(
	std::vector<fastjet::PseudoJet> const & partons
	) const;
	bool pass_resummation_cuts(
	std::vector<fastjet::PseudoJet> const & jets
	) const;
	int sample_ng(std::vector<fastjet::PseudoJet> const & Born_jets);
	int sample_ng_jets(int ng, std::vector<fastjet::PseudoJet> const & Born_jets);
	double probability_in_jet(
	std::vector<fastjet::PseudoJet> const & Born_jets
	) const;
	std::vector<fastjet::PseudoJet> gen_non_jet(
	int ng_non_jet,
	double ptmin, double ptmax
	);
	void rescale_rapidities(
	std::vector<fastjet::PseudoJet> & partons,
	double ymin, double ymax
	);
	std::vector<fastjet::PseudoJet> reshuffle(
	std::vector<fastjet::PseudoJet> const & Born_jets,
	fastjet::PseudoJet const & q
	);
	bool jets_ok(
	std::vector<fastjet::PseudoJet> const & Born_jets,
	std::vector<fastjet::PseudoJet> const & partons
	) const;
	void reconstruct_incoming(std::array<Sparticle, 2> const & Born_incoming);
	double phase_space_normalisation(
	int num_Born_jets,
	int num_res_partons
	) const;
	std::vector<fastjet::PseudoJet> split(
	std::vector<fastjet::PseudoJet> const & jets, int ng_jets
	);
	std::vector<int> distribute_jet_partons(
	int ng_jets, std::vector<fastjet::PseudoJet> const & jets
	);
	std::vector<fastjet::PseudoJet> split(
	std::vector<fastjet::PseudoJet> const & jets,
	std::vector<int> const & np_in_jet
	);
	bool split_preserved_jets(
	std::vector<fastjet::PseudoJet> const & jets,
	std::vector<fastjet::PseudoJet> const & jet_partons
	) const;
	template<class Particle>
	Particle const & most_backward_FKL(
	std::vector<Particle> const & partons
	) const;
	template<class Particle>
	Particle const & most_forward_FKL(
	std::vector<Particle> const & partons
	) const;
	template<class Particle>
	Particle & most_backward_FKL(std::vector<Particle> & partons) const;
	template<class Particle>
	Particle & most_forward_FKL(std::vector<Particle> & partons) const;
	bool extremal_FKL_ok(
	std::vector<fastjet::PseudoJet> const & partons
	) const;

	bool momentum_conserved(double ep) const;

	bool unob_, unof_;

	double weight_;

	double extpartonptmin_;
	double jetptmin_, Born_jetptmin_;
	fastjet::JetDefinition jet_def_, Born_jet_def_;

	std::array<Sparticle, 2> incoming_;
	std::vector<Sparticle> outgoing_;

	static CLHEP::Ranlux64Engine ran_;
	HejSplit splitter_;
	};

	}

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