[u/mrichter/AliRoot.git] / HBTAN / AliHBTCrab.cxx

#include "AliHBTCrab.h"
//______________________________________________________________________
/////////////////////////////////////////////////////////////////////////
//                                                                     //
// AliRoot wrapper to CRAB                                             //
// taken from http://www.nscl.msu.edu/~pratt/freecodes/crab/home.html  //
// written by Scott Pratt                                              //
//                                                                     //
//                                                                     //
/////////////////////////////////////////////////////////////////////////
 
#include "AliHBTPair.h"
#include "AliVAODParticle.h"
#include "TDatabasePDG.h"
#include <TMath.h>

#include "volya_complex.h"

AliHBTCrab* AliHBTCrab::fgCrab = 0x0;

const Double_t AliHBTCrab::fgkWcons = 1./0.1973;
const Double_t AliHBTCrab::fgkROOT2=1.41421356237309504880;
#ifdef __DECCXX
const complex AliHBTCrab::fgkCI(0.0,1.0);
#else
const doublecomplex AliHBTCrab::fgkCI(0.0,1.0);
#endif

/************************************************************/

AliHBTCrab* AliHBTCrab::Instance()
{
// returns instance of class
 if (fgCrab == 0x0)
  {
    fgCrab = new AliHBTCrab();
  }
 return fgCrab;
}
//===================================================================

void AliHBTCrab::Set()
{
//sets this as weighitng class
 Info("Set","Setting CRAB as Weighing Class");
 
 if ( fgWeights == 0x0 )  
  {
    fgWeights = AliHBTCrab::Instance();
    return;
  }  
 if ( fgWeights == AliHBTCrab::Instance() ) return;
 delete fgWeights;
 fgWeights = AliHBTCrab::Instance();
}
//===================================================================

AliHBTCrab::AliHBTCrab():
fBreitWigner(kFALSE),
fReducedMom(kTRUE),
fMaxMomentum(100.0)
{
  //ctor
  if(fgCrab)
   {
     Fatal("AliHBTCrab","Do not use constructor directly. Use Instance() instead.");
   }
}
//===================================================================

AliHBTCrab::AliHBTCrab(const AliHBTCrab &/*source*/):
AliHBTWeights(),
fBreitWigner(kFALSE),
fReducedMom(kTRUE),
fMaxMomentum(100.0)
{
  //ctor
}
//===================================================================
AliHBTCrab & AliHBTCrab::operator=(const AliHBTCrab& /*source*/)
{
//cpy constructor
 return *AliHBTCrab::Instance();
}

void AliHBTCrab::Init(Int_t pid1,Int_t pid2)
{
//Initialization method
  fMass1 = TDatabasePDG::Instance()->GetParticle(pid1)->Mass();
  fMass2 = TDatabasePDG::Instance()->GetParticle(pid2)->Mass();
  fInteractionWsym = 1.0;
  fInteractionWanti = 0.0;
  fInteractionWnosym = 0.0;
  fInteractionDelk  = 1.0;
  fInteractionNkmax = 100;
     
  fPid1 = pid1;   
  fPid2 = pid2;
}
//===================================================================

Bool_t AliHBTCrab::SetConfig(const AliHBTPair* pair)
{
//returns the SetConfig
  
  Int_t pdg1 = pair->Particle1()->GetPdgCode();
  Int_t pdg2 = pair->Particle2()->GetPdgCode();
  
  if ( ( pdg1 == fPid1) && ( pdg2  == fPid2) ) return kFALSE;
  else Init (pdg1,pdg2);
  
  return kTRUE;
}
//===================================================================

Double_t AliHBTCrab::GetWeight(const AliHBTPair* partpair)
{
//returns the weight
  Double_t qred, r, qdotr, mom;
  Int_t test;
  
  SetConfig(partpair);
  
  GetComQuantities(partpair, &qred, &r, &qdotr, &mom, &test);
  if(test==0) 
   {
     Info("GetWeight","Test is 0");
   }
  Double_t corr = CorrCalc(qred,qdotr,r);
  
  return corr;
}
//===================================================================

void AliHBTCrab::GetComQuantities(const AliHBTPair* pair, 
       double *qred,double *r,double *qdotr,double *mom, int *test)
{
//************************************
//  ALICE //

 double p1[4]; 
 double p2[4]; 
 double r1[4]; 
 double r2[4]; 
 
 static const Double_t kCmToFm = 1.e13;
// static const Double_t cmtoOneOverGeV = kCmToFm*fgkWcons;
 
 AliVAODParticle *part1 = pair->Particle1();
 AliVAODParticle *part2 = pair->Particle2();

 p1[0] = part1->E()*1000.0;
 p1[1] = part1->Px()*1000.0;
 p1[2] = part1->Py()*1000.0;
 p1[3] = part1->Pz()*1000.0;
 
 p2[0] = part2->E()*1000.0;
 p2[1] = part2->Px()*1000.0;
 p2[2] = part2->Py()*1000.0;
 p2[3] = part2->Pz()*1000.0;

 r1[0] = part1->T();
 r1[1] = part1->Vx()*kCmToFm;
 r1[2] = part1->Vy()*kCmToFm;
 r1[3] = part1->Vz()*kCmToFm;

 r2[0] = part2->T();
 r2[1] = part2->Vx()*kCmToFm;
 r2[2] = part2->Vy()*kCmToFm;
 r2[3] = part2->Vz()*kCmToFm;

//  END OF ALICE STUFF

// This code is written by Scott Pratt
// taken from http://www.nscl.msu.edu/~pratt/freecodes/crab/home.html
  int alpha;
  double kdotr;
  double momtest;
  if (fReducedMom)
   {
     momtest=4.0*fMaxMomentum*fMaxMomentum;
   }  
  else
   {
     momtest=fMaxMomentum*fMaxMomentum;
   }  
   
  double ptot2,pdotr,pp,rr;
  
  if ( part1->GetPdgCode() == part2->GetPdgCode() )
   {
    *test=1;
    *mom=-(p2[0]-p1[0])*(p2[0]-p1[0]);
    for(alpha=1;alpha<4;alpha++){
      *mom=*mom+(p2[alpha]-p1[alpha])*(p2[alpha]-p1[alpha]);
    }
   //#if ! defined MIXED_PAIRS_FOR_DENOM
   //  if(*mom>momtest){
   //    *test=0;
   //    return;
   //  }
   //#endif
    pp=(p1[0]+p2[0]);
    rr=(r2[0]-r1[0]);
    pdotr=pp*rr;
    kdotr=(p2[0]-p1[0])*rr;
    ptot2=pp*pp;
    *r=-rr*rr;
    for(alpha=1;alpha<4;alpha++){
      pp=(p1[alpha]+p2[alpha]);
      rr=(r2[alpha]-r1[alpha]);
      pdotr=pdotr-pp*rr;
      kdotr=kdotr-(p2[alpha]-p1[alpha])*rr;
      ptot2=ptot2-pp*pp;
      *r=*r+rr*rr;
    }
    *mom=sqrt(*mom);
    *qred=0.5**mom;

    if (fReducedMom)
     {
      *mom=*qred;
     } 

    *qdotr=0.5*kdotr;
    *r=sqrt(*r+pdotr*pdotr/ptot2);
   }  
  else //identical
  {
  //  const double  kdotp=fMass2*fMass2-fMass1*fMass1;
   const double  kdotp = part2->Mass()*part2->Mass()- part1->Mass()*part1->Mass();
   *test=1;
   *mom=-(p2[0]-p1[0])*(p2[0]-p1[0]);
   ptot2=(p1[0]+p2[0])*(p1[0]+p2[0]);
   for(alpha=1;alpha<4;alpha++){
     *mom=*mom+(p2[alpha]-p1[alpha])*(p2[alpha]-p1[alpha]);
     ptot2=ptot2-(p1[alpha]+p2[alpha])*(p1[alpha]+p2[alpha]);
   }
   *mom=*mom+kdotp*kdotp/ptot2;
  //#if ! defined MIXED_PAIRS_FOR_DENOM
  //  if(*mom>momtest){
  //    *test=0;
  //    return;
  //  }
  //#endif
   pp=(p1[0]+p2[0]);
   rr=(r2[0]-r1[0]);
   pdotr=pp*rr;
   kdotr=(p2[0]-p1[0])*rr;
   *r=-rr*rr;
   for(alpha=1;alpha<4;alpha++){
     pp=(p1[alpha]+p2[alpha]);
     rr=(r2[alpha]-r1[alpha]);
     pdotr=pdotr-pp*rr;
     kdotr=kdotr-(p2[alpha]-p1[alpha])*rr;
     *r=*r+rr*rr;
   }
   kdotr=(-kdotr+kdotp*pdotr/ptot2);
   *mom=sqrt(*mom);
   *qred=0.5**mom;

   if (fReducedMom)
    {
     *mom=*qred;
    } 

   *qdotr=0.5*kdotr;
   *r=sqrt(*r+pdotr*pdotr/ptot2);
  }//not identical  

  return;
}


//===================================================================

double  AliHBTCrab::CorrCalc(double trueqred,double trueqdotr,double truer)
{
//#define REDUCED_MOM
// This code is written by Scott Pratt
// taken from http://www.nscl.msu.edu/~pratt/freecodes/crab/home.html
  double eta,arg,corr0;
//  double xx,xxprime,xxjj,p1,zk;
//  int jj,kk,ipart,ipartcount,ispin;
  int kk;
  double wsymleftover,wantileftover,wnosymleftover;
  double qred,qdotr,r;
//  const double rmass=fMass1*fMass2/(fMass1+fMass2);
#ifdef __DECCXX
  complex cphi1,cphi2,cphis,cphia;
#else
  doublecomplex cphi1,cphi2,cphis,cphia;
#endif

  arg=trueqdotr/197.323-2.0*TMath::Pi()*TMath::Floor(trueqdotr/(197.323*2.0*TMath::Pi()));
  cphi1=exp(fgkCI*arg);
  cphis=fgkROOT2*real(cphi1);
  cphia=fgkCI*fgkROOT2*imag(cphi1);
  corr0=real(fInteractionWsym*cphis*conj(cphis)
	     +fInteractionWanti*cphia*conj(cphia)
	     +fInteractionWnosym*cphi1*conj(cphi1));
  goto OUTSIDE_INTERACTION_RANGE;

#ifdef REDUCED_MOM
  kk=(int)TMath::Floor(trueqred/fInteractionDelk);
  qred=(0.5+kk)*fInteractionDelk;
#else
  kk=(int)TMath::Floor(2.0*trueqred/fInteractionDelk);
  qred=(0.5+kk)*fInteractionDelk/2.0;
#endif
  qdotr=trueqdotr*qred/trueqred;
  if(kk>=fInteractionNkmax){
    corr0=1.0;
    goto OUTSIDE_INTERACTION_RANGE;
  }
  r=truer;

  eta=0.0;
  arg=qdotr/197.323-2.0*TMath::Pi()*TMath::Floor(qdotr/(197.323*2.0*TMath::Pi()));
  cphi1=exp(fgkCI*arg);
  cphi2=conj(cphi1);

  cphis=(cphi1+cphi2)/fgkROOT2;
  cphia=(cphi1-cphi2)/fgkROOT2;
  corr0=0.0;
  /* If there are corrections for strong interactions, add the
     change for each partial wave.  If npartial = 0 then there
     are no strong int. corrections. */
  wsymleftover=fInteractionWsym;
  wantileftover=fInteractionWanti;
  wnosymleftover=fInteractionWnosym;

  corr0=corr0+real(wsymleftover*cphis*conj(cphis)
		   +wantileftover*cphia*conj(cphia)
		   +wnosymleftover*cphi1*conj(cphi1));
OUTSIDE_INTERACTION_RANGE:

#ifdef BREIT_WIGNER
  corr0=corr0+bwcalc(trueqred,truer);
#endif

  return corr0;
}

#ifdef __DECCXX
complex AliHBTCrab::CGamma(complex c){
/* This calc.s gamma functions which are in the form gamma(n+i*y)
   where n is an int and y is real. */
// This code is written by Scott Pratt
// taken from http://www.nscl.msu.edu/~pratt/freecodes/crab/home.html
#else
doublecomplex AliHBTCrab::CGamma(doublecomplex c){
/* This calc.s gamma functions which are in the form gamma(n+i*y)
   where n is an int and y is real. */
// This code is written by Scott Pratt
// taken from http://www.nscl.msu.edu/~pratt/freecodes/crab/home.html
#endif
#ifdef __DECCXX
  complex cg,cphase;
#else
  doublecomplex cg,cphase;
#endif
  int mm,j;
  double x,y,phase,delp,cgmag;
  x=real(c);
  y=imag(c);
  phase=-TMath::E()*y;
  for(j=1;j<=100000;j++){
    delp=(y/(double)j)-atan(y/(double)j);
    phase=phase+delp;
    if(TMath::Abs(delp)<1E-10) goto CGamma_ESCAPE;
  }
  printf("oops not accurate enough, increase jmax\n");
CGamma_ESCAPE:
  phase=phase-2.0*TMath::Pi()*TMath::Floor(phase/(2.0*TMath::Pi()));
  cphase=exp(fgkCI*phase);
  cgmag=sqrt(TMath::Pi()*y/sinh(TMath::Pi()*y));
  mm=(int)TMath::Floor(x+0.5);
  cg=cgmag*cphase;
  if(mm<1){
    for(j=1;j<=-mm+1;j++){
      cg=cg/(1.0+(double)(-j)+fgkCI*y);
    }
  }
  if(mm>1) {
    for(j=1;j<=mm-1;j++){
      cg=cg*((double)(j)+fgkCI*y);
    }
  }
  return cg;
}
Commit	Line	Data
dd82cadc	1	#include "AliHBTCrab.h"
	2	//______________________________________________________________________
	3	/////////////////////////////////////////////////////////////////////////
	4	// //
	5	// AliRoot wrapper to CRAB //
	6	// taken from http://www.nscl.msu.edu/~pratt/freecodes/crab/home.html //
	7	// written by Scott Pratt //
	8	// //
c114f4f8	9	// //
dd82cadc	10	/////////////////////////////////////////////////////////////////////////
f93c53d8	11
dd82cadc	12	#include "AliHBTPair.h"
78d7c6d3	13	#include "AliVAODParticle.h"
78d7c6d3	14	#include "TDatabasePDG.h"
dd82cadc	15	#include <TMath.h>
dd82cadc	16
	17	#include "volya_complex.h"
	18
dd82cadc	19	AliHBTCrab* AliHBTCrab::fgCrab = 0x0;
	20
	21	const Double_t AliHBTCrab::fgkWcons = 1./0.1973;
	22	const Double_t AliHBTCrab::fgkROOT2=1.41421356237309504880;
8882f543	23	#ifdef __DECCXX
c114f4f8	24	const complex AliHBTCrab::fgkCI(0.0,1.0);
8882f543	25	#else
c031a417	26	const doublecomplex AliHBTCrab::fgkCI(0.0,1.0);
8882f543	27	#endif
dd82cadc	28
	29	/************************************************************/
	30
	31	AliHBTCrab* AliHBTCrab::Instance()
	32	{
	33	// returns instance of class
	34	if (fgCrab == 0x0)
	35	{
	36	fgCrab = new AliHBTCrab();
	37	}
	38	return fgCrab;
	39	}
	40	//===================================================================
c114f4f8	41
dd82cadc	42	void AliHBTCrab::Set()
dd82cadc	43	{
c114f4f8	44	//sets this as weighitng class
dd82cadc	45	Info("Set","Setting CRAB as Weighing Class");
	46
	47	if ( fgWeights == 0x0 )
	48	{
	49	fgWeights = AliHBTCrab::Instance();
	50	return;
	51	}
	52	if ( fgWeights == AliHBTCrab::Instance() ) return;
	53	delete fgWeights;
	54	fgWeights = AliHBTCrab::Instance();
	55	}
	56	//===================================================================
	57
	58	AliHBTCrab::AliHBTCrab():
	59	fBreitWigner(kFALSE),
	60	fReducedMom(kTRUE),
	61	fMaxMomentum(100.0)
	62	{
	63	//ctor
8ef3740b	64	if(fgCrab)
	65	{
	66	Fatal("AliHBTCrab","Do not use constructor directly. Use Instance() instead.");
	67	}
dd82cadc	68	}
dd82cadc	69	//===================================================================
c031a417	70
	71	AliHBTCrab::AliHBTCrab(const AliHBTCrab &/source/):
	72	AliHBTWeights(),
	73	fBreitWigner(kFALSE),
	74	fReducedMom(kTRUE),
	75	fMaxMomentum(100.0)
	76	{
	77	//ctor
	78	}
	79	//===================================================================
34914285	80	AliHBTCrab & AliHBTCrab::operator=(const AliHBTCrab& /source/)
c031a417	81	{
	82	//cpy constructor
	83	return *AliHBTCrab::Instance();
	84	}
	85
dd82cadc	86	void AliHBTCrab::Init(Int_t pid1,Int_t pid2)
dd82cadc	87	{
c031a417	88	//Initialization method
c114f4f8	89	fMass1 = TDatabasePDG::Instance()->GetParticle(pid1)->Mass();
	90	fMass2 = TDatabasePDG::Instance()->GetParticle(pid2)->Mass();
	91	fInteractionWsym = 1.0;
	92	fInteractionWanti = 0.0;
	93	fInteractionWnosym = 0.0;
	94	fInteractionDelk = 1.0;
	95	fInteractionNkmax = 100;
dd82cadc	96
	97	fPid1 = pid1;
	98	fPid2 = pid2;
dd82cadc	99	}
c031a417	100	//===================================================================
dd82cadc	101
	102	Bool_t AliHBTCrab::SetConfig(const AliHBTPair* pair)
	103	{
c114f4f8	104	//returns the SetConfig
c114f4f8	105
dd82cadc	106	Int_t pdg1 = pair->Particle1()->GetPdgCode();
	107	Int_t pdg2 = pair->Particle2()->GetPdgCode();
	108
	109	if ( ( pdg1 == fPid1) && ( pdg2 == fPid2) ) return kFALSE;
	110	else Init (pdg1,pdg2);
	111
	112	return kTRUE;
	113	}
	114	//===================================================================
	115
	116	Double_t AliHBTCrab::GetWeight(const AliHBTPair* partpair)
	117	{
c114f4f8	118	//returns the weight
dd82cadc	119	Double_t qred, r, qdotr, mom;
	120	Int_t test;
	121
	122	SetConfig(partpair);
	123
c114f4f8	124	GetComQuantities(partpair, &qred, &r, &qdotr, &mom, &test);
dd82cadc	125	if(test==0)
	126	{
	127	Info("GetWeight","Test is 0");
	128	}
c114f4f8	129	Double_t corr = CorrCalc(qred,qdotr,r);
dd82cadc	130
	131	return corr;
	132	}
	133	//===================================================================
	134
c114f4f8	135	void AliHBTCrab::GetComQuantities(const AliHBTPair* pair,
dd82cadc	136	double qred,double r,double qdotr,double mom, int *test)
c031a417	137	{
dd82cadc	138	//************************************
	139	// ALICE //
	140
	141	double p1[4];
	142	double p2[4];
	143	double r1[4];
	144	double r2[4];
	145
c114f4f8	146	static const Double_t kCmToFm = 1.e13;
c114f4f8	147	// static const Double_t cmtoOneOverGeV = kCmToFm*fgkWcons;
dd82cadc	148
78d7c6d3	149	AliVAODParticle *part1 = pair->Particle1();
78d7c6d3	150	AliVAODParticle *part2 = pair->Particle2();
dd82cadc	151
78d7c6d3	152	p1[0] = part1->E()*1000.0;
dd82cadc	153	p1[1] = part1->Px()*1000.0;
	154	p1[2] = part1->Py()*1000.0;
	155	p1[3] = part1->Pz()*1000.0;
	156
78d7c6d3	157	p2[0] = part2->E()*1000.0;
dd82cadc	158	p2[1] = part2->Px()*1000.0;
	159	p2[2] = part2->Py()*1000.0;
	160	p2[3] = part2->Pz()*1000.0;
	161
	162	r1[0] = part1->T();
c114f4f8	163	r1[1] = part1->Vx()*kCmToFm;
	164	r1[2] = part1->Vy()*kCmToFm;
	165	r1[3] = part1->Vz()*kCmToFm;
dd82cadc	166
dd82cadc	167	r2[0] = part2->T();
c114f4f8	168	r2[1] = part2->Vx()*kCmToFm;
	169	r2[2] = part2->Vy()*kCmToFm;
	170	r2[3] = part2->Vz()*kCmToFm;
dd82cadc	171
	172	// END OF ALICE STUFF
	173
	174	// This code is written by Scott Pratt
	175	// taken from http://www.nscl.msu.edu/~pratt/freecodes/crab/home.html
	176	int alpha;
	177	double kdotr;
f93c53d8	178	double momtest;
dd82cadc	179	if (fReducedMom)
dd82cadc	180	{
f93c53d8	181	momtest=4.0fMaxMomentumfMaxMomentum;
dd82cadc	182	}
	183	else
	184	{
f93c53d8	185	momtest=fMaxMomentum*fMaxMomentum;
dd82cadc	186	}
	187
	188	double ptot2,pdotr,pp,rr;
	189
	190	if ( part1->GetPdgCode() == part2->GetPdgCode() )
	191	{
	192	*test=1;
	193	mom=-(p2[0]-p1[0])(p2[0]-p1[0]);
	194	for(alpha=1;alpha<4;alpha++){
	195	mom=mom+(p2[alpha]-p1[alpha])*(p2[alpha]-p1[alpha]);
	196	}
	197	//#if ! defined MIXED_PAIRS_FOR_DENOM
	198	// if(*mom>momtest){
	199	// *test=0;
	200	// return;
	201	// }
	202	//#endif
	203	pp=(p1[0]+p2[0]);
	204	rr=(r2[0]-r1[0]);
	205	pdotr=pp*rr;
	206	kdotr=(p2[0]-p1[0])*rr;
	207	ptot2=pp*pp;
	208	r=-rrrr;
	209	for(alpha=1;alpha<4;alpha++){
	210	pp=(p1[alpha]+p2[alpha]);
	211	rr=(r2[alpha]-r1[alpha]);
	212	pdotr=pdotr-pp*rr;
	213	kdotr=kdotr-(p2[alpha]-p1[alpha])*rr;
	214	ptot2=ptot2-pp*pp;
	215	r=r+rr*rr;
	216	}
	217	mom=sqrt(mom);
	218	qred=0.5*mom;
	219
	220	if (fReducedMom)
	221	{
	222	mom=qred;
	223	}
	224
	225	qdotr=0.5kdotr;
	226	r=sqrt(r+pdotr*pdotr/ptot2);
	227	}
	228	else //identical
	229	{
c114f4f8	230	// const double kdotp=fMass2fMass2-fMass1fMass1;
78d7c6d3	231	const double kdotp = part2->Mass()part2->Mass()- part1->Mass()part1->Mass();
dd82cadc	232	*test=1;
	233	mom=-(p2[0]-p1[0])(p2[0]-p1[0]);
	234	ptot2=(p1[0]+p2[0])*(p1[0]+p2[0]);
	235	for(alpha=1;alpha<4;alpha++){
	236	mom=mom+(p2[alpha]-p1[alpha])*(p2[alpha]-p1[alpha]);
	237	ptot2=ptot2-(p1[alpha]+p2[alpha])*(p1[alpha]+p2[alpha]);
	238	}
	239	mom=mom+kdotp*kdotp/ptot2;
	240	//#if ! defined MIXED_PAIRS_FOR_DENOM
	241	// if(*mom>momtest){
	242	// *test=0;
	243	// return;
	244	// }
	245	//#endif
	246	pp=(p1[0]+p2[0]);
	247	rr=(r2[0]-r1[0]);
	248	pdotr=pp*rr;
	249	kdotr=(p2[0]-p1[0])*rr;
	250	r=-rrrr;
	251	for(alpha=1;alpha<4;alpha++){
	252	pp=(p1[alpha]+p2[alpha]);
	253	rr=(r2[alpha]-r1[alpha]);
	254	pdotr=pdotr-pp*rr;
	255	kdotr=kdotr-(p2[alpha]-p1[alpha])*rr;
	256	r=r+rr*rr;
	257	}
	258	kdotr=(-kdotr+kdotp*pdotr/ptot2);
	259	mom=sqrt(mom);
	260	qred=0.5*mom;
	261
	262	if (fReducedMom)
	263	{
	264	mom=qred;
	265	}
	266
	267	qdotr=0.5kdotr;
	268	r=sqrt(r+pdotr*pdotr/ptot2);
	269	}//not identical
	270
	271	return;
	272	}
	273
	274
	275	//===================================================================
	276
c114f4f8	277	double AliHBTCrab::CorrCalc(double trueqred,double trueqdotr,double truer)
dd82cadc	278	{
	279	//#define REDUCED_MOM
	280	// This code is written by Scott Pratt
	281	// taken from http://www.nscl.msu.edu/~pratt/freecodes/crab/home.html
f93c53d8	282	double eta,arg,corr0;
	283	// double xx,xxprime,xxjj,p1,zk;
	284	// int jj,kk,ipart,ipartcount,ispin;
	285	int kk;
c031a417	286	double wsymleftover,wantileftover,wnosymleftover;
dd82cadc	287	double qred,qdotr,r;
c114f4f8	288	// const double rmass=fMass1*fMass2/(fMass1+fMass2);
8882f543	289	#ifdef __DECCXX
	290	complex cphi1,cphi2,cphis,cphia;
	291	#else
c031a417	292	doublecomplex cphi1,cphi2,cphis,cphia;
8882f543	293	#endif
dd82cadc	294
3294e9ff	295	arg=trueqdotr/197.323-2.0TMath::Pi()TMath::Floor(trueqdotr/(197.3232.0TMath::Pi()));
c114f4f8	296	cphi1=exp(fgkCI*arg);
dd82cadc	297	cphis=fgkROOT2*real(cphi1);
c114f4f8	298	cphia=fgkCIfgkROOT2imag(cphi1);
	299	corr0=real(fInteractionWsymcphisconj(cphis)
	300	+fInteractionWanticphiaconj(cphia)
	301	+fInteractionWnosymcphi1conj(cphi1));
dd82cadc	302	goto OUTSIDE_INTERACTION_RANGE;
	303
	304	#ifdef REDUCED_MOM
c114f4f8	305	kk=(int)TMath::Floor(trueqred/fInteractionDelk);
c114f4f8	306	qred=(0.5+kk)*fInteractionDelk;
dd82cadc	307	#else
c114f4f8	308	kk=(int)TMath::Floor(2.0*trueqred/fInteractionDelk);
c114f4f8	309	qred=(0.5+kk)*fInteractionDelk/2.0;
dd82cadc	310	#endif
dd82cadc	311	qdotr=trueqdotr*qred/trueqred;
c114f4f8	312	if(kk>=fInteractionNkmax){
dd82cadc	313	corr0=1.0;
	314	goto OUTSIDE_INTERACTION_RANGE;
	315	}
	316	r=truer;
	317
	318	eta=0.0;
3294e9ff	319	arg=qdotr/197.323-2.0TMath::Pi()TMath::Floor(qdotr/(197.3232.0TMath::Pi()));
c114f4f8	320	cphi1=exp(fgkCI*arg);
dd82cadc	321	cphi2=conj(cphi1);
	322
	323	cphis=(cphi1+cphi2)/fgkROOT2;
	324	cphia=(cphi1-cphi2)/fgkROOT2;
	325	corr0=0.0;
	326	/* If there are corrections for strong interactions, add the
	327	change for each partial wave. If npartial = 0 then there
	328	are no strong int. corrections. */
c031a417	329	wsymleftover=fInteractionWsym;
	330	wantileftover=fInteractionWanti;
	331	wnosymleftover=fInteractionWnosym;
dd82cadc	332
c031a417	333	corr0=corr0+real(wsymleftovercphisconj(cphis)
	334	+wantileftovercphiaconj(cphia)
	335	+wnosymleftovercphi1conj(cphi1));
dd82cadc	336	OUTSIDE_INTERACTION_RANGE:
	337
	338	#ifdef BREIT_WIGNER
	339	corr0=corr0+bwcalc(trueqred,truer);
	340	#endif
	341
	342	return corr0;
	343	}
	344
8882f543	345	#ifdef __DECCXX
c114f4f8	346	complex AliHBTCrab::CGamma(complex c){
c031a417	347	/* This calc.s gamma functions which are in the form gamma(n+i*y)
	348	where n is an int and y is real. */
	349	// This code is written by Scott Pratt
	350	// taken from http://www.nscl.msu.edu/~pratt/freecodes/crab/home.html
8882f543	351	#else
c031a417	352	doublecomplex AliHBTCrab::CGamma(doublecomplex c){
	353	/* This calc.s gamma functions which are in the form gamma(n+i*y)
	354	where n is an int and y is real. */
dd82cadc	355	// This code is written by Scott Pratt
dd82cadc	356	// taken from http://www.nscl.msu.edu/~pratt/freecodes/crab/home.html
c031a417	357	#endif
8882f543	358	#ifdef __DECCXX
	359	complex cg,cphase;
	360	#else
c031a417	361	doublecomplex cg,cphase;
8882f543	362	#endif
dd82cadc	363	int mm,j;
	364	double x,y,phase,delp,cgmag;
	365	x=real(c);
	366	y=imag(c);
	367	phase=-TMath::E()*y;
	368	for(j=1;j<=100000;j++){
	369	delp=(y/(double)j)-atan(y/(double)j);
	370	phase=phase+delp;
c114f4f8	371	if(TMath::Abs(delp)<1E-10) goto CGamma_ESCAPE;
dd82cadc	372	}
dd82cadc	373	printf("oops not accurate enough, increase jmax\n");
c114f4f8	374	CGamma_ESCAPE:
3294e9ff	375	phase=phase-2.0TMath::Pi()TMath::Floor(phase/(2.0*TMath::Pi()));
c114f4f8	376	cphase=exp(fgkCI*phase);
dd82cadc	377	cgmag=sqrt(TMath::Pi()y/sinh(TMath::Pi()y));
3294e9ff	378	mm=(int)TMath::Floor(x+0.5);
dd82cadc	379	cg=cgmag*cphase;
	380	if(mm<1){
	381	for(j=1;j<=-mm+1;j++){
c114f4f8	382	cg=cg/(1.0+(double)(-j)+fgkCI*y);
dd82cadc	383	}
	384	}
	385	if(mm>1) {
	386	for(j=1;j<=mm-1;j++){
c114f4f8	387	cg=cg((double)(j)+fgkCIy);
dd82cadc	388	}
	389	}
	390	return cg;
	391	}