CLHEP::RandGamma Class Reference

#include <RandGamma.h>

Inheritance diagram for CLHEP::RandGamma:

Collaboration diagram for CLHEP::RandGamma:

Public Member Functions
	RandGamma (HepRandomEngine &anEngine, double k=1.0, double lambda=1.0)
	RandGamma (HepRandomEngine *anEngine, double k=1.0, double lambda=1.0)
virtual	~RandGamma ()
double	fire ()
double	fire (double k, double lambda)
void	fireArray (const int size, double *vect)
void	fireArray (const int size, double *vect, double k, double lambda)
double	operator() ()
double	operator() (double k, double lambda)
std::ostream &	put (std::ostream &os) const
std::istream &	get (std::istream &is)
std::string	name () const
HepRandomEngine &	engine ()
Public Member Functions inherited from CLHEP::HepRandom
	HepRandom ()
	HepRandom (long seed)
	HepRandom (HepRandomEngine &algorithm)
	HepRandom (HepRandomEngine *algorithm)
virtual	~HepRandom ()
double	flat ()
void	flatArray (const int size, double *vect)
double	flat (HepRandomEngine *theNewEngine)
void	flatArray (HepRandomEngine *theNewEngine, const int size, double *vect)

Static Public Member Functions
static double	shoot ()
static double	shoot (double k, double lambda)
static void	shootArray (const int size, double *vect, double k=1.0, double lambda=1.0)
static double	shoot (HepRandomEngine *anEngine)
static double	shoot (HepRandomEngine *anEngine, double k, double lambda)
static void	shootArray (HepRandomEngine *anEngine, const int size, double *vect, double k=1.0, double lambda=1.0)
static std::string	distributionName ()
Static Public Member Functions inherited from CLHEP::HepRandom
static void	setTheSeed (long seed, int lux=3)
static long	getTheSeed ()
static void	setTheSeeds (const long *seeds, int aux=-1)
static const long *	getTheSeeds ()
static void	getTheTableSeeds (long *seeds, int index)
static HepRandom *	getTheGenerator ()
static void	setTheEngine (HepRandomEngine *theNewEngine)
static HepRandomEngine *	getTheEngine ()
static void	saveEngineStatus (const char filename[]="Config.conf")
static void	restoreEngineStatus (const char filename[]="Config.conf")
static std::ostream &	saveFullState (std::ostream &os)
static std::istream &	restoreFullState (std::istream &is)
static std::ostream &	saveDistState (std::ostream &os)
static std::istream &	restoreDistState (std::istream &is)
static std::ostream &	saveStaticRandomStates (std::ostream &os)
static std::istream &	restoreStaticRandomStates (std::istream &is)
static void	showEngineStatus ()
static int	createInstance ()
static std::string	distributionName ()

Static Private Member Functions
static double	genGamma (HepRandomEngine *anEngine, double k, double lambda)

Private Attributes
std::shared_ptr< HepRandomEngine >	localEngine
double	defaultK
double	defaultLambda

Additional Inherited Members
Static Protected Attributes inherited from CLHEP::HepRandom
static const long	seedTable [215][2]

Detailed Description

Author

Definition at line 37 of file RandGamma.h.

Constructor & Destructor Documentation

RandGamma() [1/2]

CLHEP::RandGamma::RandGamma ( HepRandomEngine &  anEngine, double  k = 1.0, double  lambda = 1.0  )

inline

RandGamma() [2/2]

CLHEP::RandGamma::RandGamma ( HepRandomEngine *  anEngine, double  k = 1.0, double  lambda = 1.0  )

inline

~RandGamma()

CLHEP::RandGamma::~RandGamma ( )

virtual

Definition at line 28 of file RandGamma.cc.

                      {
}

Member Function Documentation

distributionName()

static std::string CLHEP::RandGamma::distributionName ( )

inlinestatic

Definition at line 99 of file RandGamma.h.

{return "RandGamma";}  

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engine()

HepRandomEngine & CLHEP::RandGamma::engine ( )

virtual

Reimplemented from CLHEP::HepRandom.

Definition at line 26 of file RandGamma.cc.

{return *localEngine;}

fire() [1/2]

double CLHEP::RandGamma::fire ( )

inline

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fire() [2/2]

double CLHEP::RandGamma::fire	(	double	k,
		double	lambda
	)

Definition at line 41 of file RandGamma.cc.

                                                {
  return genGamma( localEngine.get(), k, lambda );
}

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fireArray() [1/2]

void CLHEP::RandGamma::fireArray	(	const int	size,
		double *	vect
	)

Definition at line 60 of file RandGamma.cc.

{
  for( double* v = vect; v != vect + size; ++v )
    *v = fire(defaultK,defaultLambda);
}

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fireArray() [2/2]

void CLHEP::RandGamma::fireArray	(	const int	size,
		double *	vect,
		double	k,
		double	lambda
	)

Definition at line 66 of file RandGamma.cc.

{
  for( double* v = vect; v != vect + size; ++v )
    *v = fire(k,lambda);
}

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genGamma()

double CLHEP::RandGamma::genGamma ( HepRandomEngine *  anEngine, double  k, double  lambda  )

staticprivate

Definition at line 73 of file RandGamma.cc.

                                                         {
/*************************************************************************
 *         Gamma Distribution - Rejection algorithm gs combined with     *
 *                              Acceptance complement method gd          *
 *************************************************************************/

  static CLHEP_THREAD_LOCAL double aa = -1.0, aaa = -1.0, b, c, d, e, r, s, si, ss, q0;
  static const double q1 = 0.0416666664, q2 =  0.0208333723, q3 = 0.0079849875,
       q4 = 0.0015746717, q5 = -0.0003349403, q6 = 0.0003340332,
       q7 = 0.0006053049, q8 = -0.0004701849, q9 = 0.0001710320,
       a1 = 0.333333333,  a2 = -0.249999949,  a3 = 0.199999867,
       a4 =-0.166677482,  a5 =  0.142873973,  a6 =-0.124385581,
       a7 = 0.110368310,  a8 = -0.112750886,  a9 = 0.104089866,
       e1 = 1.000000000,  e2 =  0.499999994,  e3 = 0.166666848,
       e4 = 0.041664508,  e5 =  0.008345522,  e6 = 0.001353826,
       e7 = 0.000247453;

double gds,p,q,t,sign_u,u,v,w,x;
double v1,v2,v12;

// Check for invalid input values

 if( a <= 0.0 ) return (-1.0);
 if( lambda <= 0.0 ) return (-1.0);

 if (a < 1.0)
   {          // CASE A: Acceptance rejection algorithm gs
    b = 1.0 + 0.36788794412 * a;       // Step 1
    for(;;)
      {
       p = b * anEngine->flat();
       if (p <= 1.0)
      {                            // Step 2. Case gds <= 1
       gds = std::exp(std::log(p) / a);
       if (std::log(anEngine->flat()) <= -gds) return(gds/lambda);
      }
       else
      {                            // Step 3. Case gds > 1
       gds = - std::log ((b - p) / a);
       if (std::log(anEngine->flat()) <= ((a - 1.0) * std::log(gds))) return(gds/lambda);
      }
      }
   }
 else
   {          // CASE B: Acceptance complement algorithm gd
    if (a != aa)
       {                               // Step 1. Preparations
    aa = a;
    ss = a - 0.5;
    s = std::sqrt(ss);
    d = 5.656854249 - 12.0 * s;
       }
                                              // Step 2. Normal deviate
    do {
      v1 = 2.0 * anEngine->flat() - 1.0;
      v2 = 2.0 * anEngine->flat() - 1.0;
      v12 = v1*v1 + v2*v2;
    } while ( v12 > 1.0 );
    t = v1*std::sqrt(-2.0*std::log(v12)/v12);
    x = s + 0.5 * t;
    gds = x * x;
    if (t >= 0.0) return(gds/lambda);         // Immediate acceptance

    u = anEngine->flat();            // Step 3. Uniform random number
    if (d * u <= t * t * t) return(gds/lambda); // Squeeze acceptance

    if (a != aaa)
       {                               // Step 4. Set-up for hat case
    aaa = a;
    r = 1.0 / a;
    q0 = ((((((((q9 * r + q8) * r + q7) * r + q6) * r + q5) * r + q4) *
              r + q3) * r + q2) * r + q1) * r;
    if (a > 3.686)
       {
        if (a > 13.022)
           {
        b = 1.77;
        si = 0.75;
        c = 0.1515 / s;
           }
        else
           {
        b = 1.654 + 0.0076 * ss;
        si = 1.68 / s + 0.275;
        c = 0.062 / s + 0.024;
           }
       }
    else
       {
        b = 0.463 + s - 0.178 * ss;
        si = 1.235;
        c = 0.195 / s - 0.079 + 0.016 * s;
       }
       }
    if (x > 0.0)                       // Step 5. Calculation of q
       {
    v = t / (s + s);               // Step 6.
    if (std::fabs(v) > 0.25)
       {
        q = q0 - s * t + 0.25 * t * t + (ss + ss) * std::log(1.0 + v);
       }
    else
       {
        q = q0 + 0.5 * t * t * ((((((((a9 * v + a8) * v + a7) * v + a6) *
                v + a5) * v + a4) * v + a3) * v + a2) * v + a1) * v;
       }                // Step 7. Quotient acceptance
    if (std::log(1.0 - u) <= q) return(gds/lambda);
       }

    for(;;)
       {                    // Step 8. Double exponential deviate t
    do
    {
     e = -std::log(anEngine->flat());
     u = anEngine->flat();
     u = u + u - 1.0;
     sign_u = (u > 0)? 1.0 : -1.0;
     t = b + (e * si) * sign_u;
    }
    while (t <= -0.71874483771719);   // Step 9. Rejection of t
    v = t / (s + s);                  // Step 10. New q(t)
    if (std::fabs(v) > 0.25)
       {
        q = q0 - s * t + 0.25 * t * t + (ss + ss) * std::log(1.0 + v);
       }
    else
       {
        q = q0 + 0.5 * t * t * ((((((((a9 * v + a8) * v + a7) * v + a6) *
                v + a5) * v + a4) * v + a3) * v + a2) * v + a1) * v;
       }
    if (q <= 0.0) continue;           // Step 11.
    if (q > 0.5)
       {
        w = std::exp(q) - 1.0;
       }
    else
       {
        w = ((((((e7 * q + e6) * q + e5) * q + e4) * q + e3) * q + e2) *
                     q + e1) * q;
       }                    // Step 12. Hat acceptance
    if ( c * u * sign_u <= w * std::exp(e - 0.5 * t * t))
       {
        x = s + 0.5 * t;
        return(x*x/lambda);
       }
       }
   }
}

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get()

std::istream & CLHEP::RandGamma::get ( std::istream &  is )

virtual

Reimplemented from CLHEP::HepRandom.

Definition at line 236 of file RandGamma.cc.

                                              {
  std::string inName;
  is >> inName;
  if (inName != name()) {
    is.clear(std::ios::badbit | is.rdstate());
    std::cerr << "Mismatch when expecting to read state of a "
              << name() << " distribution\n"
          << "Name found was " << inName
          << "\nistream is left in the badbit state\n";
    return is;
  }
  if (possibleKeywordInput(is, "Uvec", defaultK)) {
    std::vector<unsigned long> t(2);
    is >> defaultK >> t[0] >> t[1]; defaultK = DoubConv::longs2double(t); 
    is >> defaultLambda>>t[0]>>t[1]; defaultLambda = DoubConv::longs2double(t); 
    return is;
  }
  // is >> defaultK encompassed by possibleKeywordInput
  is >> defaultLambda;
  return is;
}

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name()

std::string CLHEP::RandGamma::name ( ) const

virtual

Reimplemented from CLHEP::HepRandom.

Definition at line 25 of file RandGamma.cc.

{return "RandGamma";}

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operator()() [1/2]

double CLHEP::RandGamma::operator() ( )

inlinevirtual

Reimplemented from CLHEP::HepRandom.

operator()() [2/2]

double CLHEP::RandGamma::operator() ( double  k, double  lambda  )

inline

put()

std::ostream & CLHEP::RandGamma::put ( std::ostream &  os ) const

virtual

Reimplemented from CLHEP::HepRandom.

Definition at line 223 of file RandGamma.cc.

                                                    {
  int pr=os.precision(20);
  std::vector<unsigned long> t(2);
  os << " " << name() << "\n";
  os << "Uvec" << "\n";
  t = DoubConv::dto2longs(defaultK);
  os << defaultK << " " << t[0] << " " << t[1] << "\n";
  t = DoubConv::dto2longs(defaultLambda);
  os << defaultLambda << " " << t[0] << " " << t[1] << "\n";
  os.precision(pr);
  return os;
}

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shoot() [1/4]

static double CLHEP::RandGamma::shoot ( )

inlinestatic

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shoot() [2/4]

double CLHEP::RandGamma::shoot ( double  k, double  lambda  )

static

Definition at line 36 of file RandGamma.cc.

                                                 {
  HepRandomEngine *anEngine = HepRandom::getTheEngine();
  return genGamma( anEngine, k, lambda );
}

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shoot() [3/4]

static double CLHEP::RandGamma::shoot ( HepRandomEngine *  anEngine )

inlinestatic

shoot() [4/4]

double CLHEP::RandGamma::shoot ( HepRandomEngine *  anEngine, double  k, double  lambda  )

static

Definition at line 31 of file RandGamma.cc.

                                                                        {
  return genGamma( anEngine, k, lambda );
}

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shootArray() [1/2]

void CLHEP::RandGamma::shootArray ( const int  size, double *  vect, double  k = 1.0, double  lambda = 1.0  )

static

Definition at line 45 of file RandGamma.cc.

{
  for( double* v = vect; v != vect + size; ++v )
    *v = shoot(k,lambda);
}

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shootArray() [2/2]

void CLHEP::RandGamma::shootArray ( HepRandomEngine *  anEngine, const int  size, double *  vect, double  k = 1.0, double  lambda = 1.0  )

static

Definition at line 52 of file RandGamma.cc.

{
  for( double* v = vect; v != vect + size; ++v )
    *v = shoot(anEngine,k,lambda);
}

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Member Data Documentation

defaultK

double CLHEP::RandGamma::defaultK

private

Definition at line 109 of file RandGamma.h.

defaultLambda

double CLHEP::RandGamma::defaultLambda

private

Definition at line 110 of file RandGamma.h.

localEngine

std::shared_ptr<HepRandomEngine> CLHEP::RandGamma::localEngine

private

Definition at line 108 of file RandGamma.h.

---

The documentation for this class was generated from the following files:

• RandGamma.h
• RandGamma.cc