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diff --git a/Shower/SplittingFunctions/HalfHalfOneSplitFn.cc b/Shower/SplittingFunctions/HalfHalfOneSplitFn.cc
--- a/Shower/SplittingFunctions/HalfHalfOneSplitFn.cc
+++ b/Shower/SplittingFunctions/HalfHalfOneSplitFn.cc
@@ -1,99 +1,100 @@
// -*- C++ -*-
//
// HalfHalfOneSplitFn.cc is a part of Herwig++ - A multi-purpose Monte Carlo event generator
// Copyright (C) 2002-2011 The Herwig Collaboration
//
// Herwig++ is licenced under version 2 of the GPL, see COPYING for details.
// Please respect the MCnet academic guidelines, see GUIDELINES for details.
//
//
// This is the implementation of the non-inlined, non-templated member
// functions of the HalfHalfOneSplitFn class.
//
#include "HalfHalfOneSplitFn.h"
#include "ThePEG/PDT/ParticleData.h"
#include "ThePEG/PDT/EnumParticles.h"
+#include "ThePEG/Utilities/Maths.h"
#include "ThePEG/Interface/ClassDocumentation.h"
#include "Herwig++/Shower/Base/ShowerParticle.h"
#include <cassert>
using namespace Herwig;
NoPIOClassDescription<HalfHalfOneSplitFn> HalfHalfOneSplitFn::initHalfHalfOneSplitFn;
// Definition of the static class description member.
void HalfHalfOneSplitFn::Init() {
static ClassDocumentation<HalfHalfOneSplitFn> documentation
("The HalfHalfOneSplitFn class implements the q -> qg splitting function");
}
double HalfHalfOneSplitFn::P(const double z, const Energy2 t,
const IdList &ids, const bool mass) const {
double val = (1. + sqr(z))/(1.-z);
if(mass) {
Energy m = getParticleData(ids[0])->mass();
val -= 2.*sqr(m)/t;
}
return colourFactor(ids)*val;
}
double HalfHalfOneSplitFn::overestimateP(const double z,
const IdList & ids) const {
return 2.*colourFactor(ids)/(1.-z);
}
double HalfHalfOneSplitFn::ratioP(const double z, const Energy2 t,
const IdList & ids, const bool mass) const {
double val = 1. + sqr(z);
if(mass) {
Energy m = getParticleData(ids[0])->mass();
val -= 2.*sqr(m)*(1.-z)/t;
}
return 0.5*val;
}
double HalfHalfOneSplitFn::integOverP(const double z,
const IdList & ids,
unsigned int PDFfactor) const {
switch (PDFfactor) {
case 0:
- return -2.*colourFactor(ids)*log(1.-z);
+ return -2.*colourFactor(ids)*Math::log1m(z);
case 1:
return 2.*colourFactor(ids)*log(z/(1.-z));
case 2:
return 2.*colourFactor(ids)/(1.-z);
case 3:
default:
throw Exception() << "HalfHalfOneSplitFn::integOverP() invalid PDFfactor = "
<< PDFfactor << Exception::runerror;
}
}
double HalfHalfOneSplitFn::invIntegOverP(const double r, const IdList & ids,
unsigned int PDFfactor) const {
switch (PDFfactor) {
case 0:
return 1. - exp(- 0.5*r/colourFactor(ids));
case 1:
return 1./(1.-exp(-0.5*r/colourFactor(ids)));
case 2:
return 1.-2.*colourFactor(ids)/r;
case 3:
default:
throw Exception() << "HalfHalfOneSplitFn::invIntegOverP() invalid PDFfactor = "
<< PDFfactor << Exception::runerror;
}
}
bool HalfHalfOneSplitFn::accept(const IdList &ids) const {
// 3 particles and in and out fermion same
if(ids.size()!=3 || ids[0]!=ids[1]) return false;
tcPDPtr q=getParticleData(ids[0]);
tcPDPtr g=getParticleData(ids[2]);
if(q->iSpin()!=PDT::Spin1Half ||
g->iSpin()!=PDT::Spin1) return false;
return checkColours(ids);
}

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