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class TUnuranDiscrDist: public TUnuranBaseDist


   TUnuranDiscrDist class for one dimensional discrete distribution.
   It is used by TUnuran to generate integer random numbers according to this distribution via
   TUnuran::SampleDiscr().

   The class can be constructed from a one-dimensional function (TF1 pointer)
   representing the discrete distribution (probability mesh function)
   (for example a TF1("f","TMath::PoissonI(x,[0])") ) or from a
   vector of probability, used by passing an iterator specifying the begin and the end of the vector.
   In the latter case the domain of the distribution will be defined by the vector, while in the first case is by
   default (0,+inf).
   a Method to set the domain of the distribution ( SetDomain ) is provided and it defines the range
   of the generated random numbers.

   The derivatives of the pdf which are used by some UNURAN methods are estimated numerically in the
   Derivative() method.
   Some extra information (like distribution mode, cdf function, probability sum, etc..)
   can be set as well otherwise will be estimated internally if required.

Function Members (Methods)

public:

	TUnuranDiscrDist(const ROOT::Math::IGenFunction& func)
	TUnuranDiscrDist(TF1* func)
	TUnuranDiscrDist(const TUnuranDiscrDist&)
	TUnuranDiscrDist(double* begin, double* end)
virtual	~TUnuranDiscrDist()
double	Cdf(int x) const
static TClass*	Class()
static TClass*	TUnuranBaseDist::Class()
virtual TUnuranDiscrDist*	Clone() const
virtual TUnuranBaseDist*	TUnuranBaseDist::Clone() const
bool	GetDomain(int& xmin, int& xmax) const
bool	HasCdf() const
bool	HasMode() const
bool	HasProbSum() const
virtual TClass*	IsA() const
virtual TClass*	TUnuranBaseDist::IsA() const
int	Mode() const
TUnuranDiscrDist&	operator=(const TUnuranDiscrDist& rhs)
TUnuranBaseDist&	TUnuranBaseDist::operator=(const TUnuranBaseDist&)
double	Pmf(int x) const
double	ProbSum() const
const vector<double>&	ProbVec() const
void	SetCdf(const ROOT::Math::IGenFunction& cdf)
void	SetCdf(TF1* cdf)
void	SetDomain(int xmin, int xmax)
void	SetMode(int mode)
void	SetProbSum(double sum)
virtual void	ShowMembers(TMemberInspector& insp, char* parent)
virtual void	TUnuranBaseDist::ShowMembers(TMemberInspector& insp, char* parent)
virtual void	Streamer(TBuffer& b)
virtual void	TUnuranBaseDist::Streamer(TBuffer& b)
void	StreamerNVirtual(TBuffer& b)
void	TUnuranBaseDist::StreamerNVirtual(TBuffer& b)

Data Members

private:

const ROOT::Math::IBaseFunctionOneDim*	fCdf	pointer to the cumulative distribution function
bool	fHasDomain	flag to control if distribution has a defined domain (otherwise is [0,INT_MAX])
bool	fHasMode	flag to control if distribution has a pre-computed mode
bool	fHasSum	flag to control if distribution has a pre-computed sum of the probabilities
int	fMode	mode of the distribution
bool	fOwnFunc	flag to control if distribution owns the funcitno pointers
vector<double>	fPVec	Vector of the probabilities
vector<double>	fPVecSum	Vector of the sum of the probabilities
const ROOT::Math::IBaseFunctionOneDim*	fPmf	pointer to a function calculating the probability
double	fSum	total sum of the probabilities in the given domain
int	fXmax	upper value of the domain
int	fXmin	lower value of the domain

Class Charts

Inheritance Inherited Members Includes Libraries

Function documentation

TUnuranDiscrDist(const ROOT::Math::IGenFunction & func )

      Constructor from a generic function object specifying the pdf

TUnuranDiscrDist(TF1 * func )

      Constructor from a TF1 objects specifying the pdf

TUnuranDiscrDist(double* begin, double* end)

      Constructor from a vector of probability

{}

virtual ~TUnuranDiscrDist()

      Destructor

TUnuranDiscrDist(const TUnuranDiscrDist &)

      Copy constructor

TUnuranDiscrDist * Clone() const

      Clone (required by base class)

{ return new TUnuranDiscrDist(*this); }

void SetCdf(const ROOT::Math::IGenFunction & cdf)

      set cdf distribution from a generic function interface. If a method requires it
      and is not set it is estimated numerically

void SetCdf(TF1 * cdf)

      set cdf distribution from a TF1 pointer.  If a method requires it
      and is not set it is estimated numerically

void SetDomain(int xmin, int xmax)

      Set the distribution domain, by default the domain is [0,INT_MAX]
      If xmin >= xmax a domain is removed

void SetMode(int mode)

      set the mode of the distribution (location of maximum probability)

{ fMode = mode; fHasMode=true;}

void SetProbSum(double sum)

      set the value of the sum of the probabilities in the given domain

{ fSum = sum; fHasSum=true; }

bool GetDomain(int& xmin, int& xmax) const

      check if distribution has domain and return in case its domain

int Mode() const

      get the mode   (x location of function maximum)

{ return fMode; }

double ProbSum() const

      return area of the pdf

{ return fSum; }

bool HasMode() const

      flag to control if distribution provides the mode

{ return fHasMode; }

bool HasProbSum() const

      flag to control if distribution provides the total area of the probability function

{ return fHasSum; }

bool HasCdf() const

      flag to control if distribution provides also a Cdf

{ return fCdf != 0; }

const std::vector<double> & ProbVec() const

      retrieve a reference to the vector of the probabilities : Prob(i)
      If the distribution is defined from a function (i.e. for distribution with undefined domain)
      the vector is empty.

{ return fPVec; }

double Pmf(int x) const

      evaluate the distribution (probability mesh function) at the integer value x.
      Used internally by UnuRan
      For integer values outside the domain the function must return 0.0

double Cdf(int x) const

       evaluate the integral (cdf)  on the given domain