The binomial distribution Random Number Generator (RNG). More...

#include "random-variable-stream.h"

Inheritance diagram for ns3::BinomialRandomVariable:

Collaboration diagram for ns3::BinomialRandomVariable:

Public Member Functions
	BinomialRandomVariable ()

virtual uint32_t	GetInteger ()
	Get the next random value drawn from the distribution. More...

uint32_t	GetInteger (uint32_t trials, uint32_t probability)
	Get the next random value drawn from the distribution. More...

double	GetValue () override
	Get the next random value drawn from the distribution. More...

double	GetValue (uint32_t trials, double probability)
	Get the next random value drawn from the distribution. More...

Public Member Functions inherited from ns3::RandomVariableStream
	RandomVariableStream ()
	Default constructor. More...

	RandomVariableStream (const RandomVariableStream &)=delete

	~RandomVariableStream () override
	Destructor. More...

int64_t	GetStream () const
	Returns the stream number for the RngStream. More...

bool	IsAntithetic () const
	Check if antithetic values will be generated. More...

RandomVariableStream &	operator= (const RandomVariableStream &)=delete

void	SetAntithetic (bool isAntithetic)
	Specify whether antithetic values should be generated. More...

void	SetStream (int64_t stream)
	Specifies the stream number for the RngStream. More...

Public Member Functions inherited from ns3::Object
	Object ()
	Constructor. More...

	~Object () override
	Destructor. More...

void	AggregateObject (Ptr< Object > other)
	Aggregate two Objects together. More...

void	Dispose ()
	Dispose of this Object. More...

AggregateIterator	GetAggregateIterator () const
	Get an iterator to the Objects aggregated to this one. More...

TypeId	GetInstanceTypeId () const override
	Get the most derived TypeId for this Object. More...

template<typename T >
Ptr< T >	GetObject () const
	Get a pointer to the requested aggregated Object. More...

template<>
Ptr< Object >	GetObject () const
	Specialization of () for objects of type ns3::Object. More...

template<typename T >
Ptr< T >	GetObject (TypeId tid) const
	Get a pointer to the requested aggregated Object by TypeId. More...

template<>
Ptr< Object >	GetObject (TypeId tid) const
	Specialization of (TypeId tid) for objects of type ns3::Object. More...

void	Initialize ()
	Invoke DoInitialize on all Objects aggregated to this one. More...

bool	IsInitialized () const
	Check if the object has been initialized. More...

Public Member Functions inherited from ns3::SimpleRefCount< Object, ObjectBase, ObjectDeleter >
	SimpleRefCount ()
	Default constructor. More...

	SimpleRefCount (const SimpleRefCount &o[[maybe_unused]])
	Copy constructor. More...

uint32_t	GetReferenceCount () const
	Get the reference count of the object. More...

SimpleRefCount &	operator= (const SimpleRefCount &o[[maybe_unused]])
	Assignment operator. More...

void	Ref () const
	Increment the reference count. More...

void	Unref () const
	Decrement the reference count. More...

Public Member Functions inherited from ns3::ObjectBase
virtual	~ObjectBase ()
	Virtual destructor. More...

void	GetAttribute (std::string name, AttributeValue &value) const
	Get the value of an attribute, raising fatal errors if unsuccessful. More...

bool	GetAttributeFailSafe (std::string name, AttributeValue &value) const
	Get the value of an attribute without raising errors. More...

void	SetAttribute (std::string name, const AttributeValue &value)
	Set a single attribute, raising fatal errors if unsuccessful. More...

bool	SetAttributeFailSafe (std::string name, const AttributeValue &value)
	Set a single attribute without raising errors. More...

bool	TraceConnect (std::string name, std::string context, const CallbackBase &cb)
	Connect a TraceSource to a Callback with a context. More...

bool	TraceConnectWithoutContext (std::string name, const CallbackBase &cb)
	Connect a TraceSource to a Callback without a context. More...

bool	TraceDisconnect (std::string name, std::string context, const CallbackBase &cb)
	Disconnect from a TraceSource a Callback previously connected with a context. More...

bool	TraceDisconnectWithoutContext (std::string name, const CallbackBase &cb)
	Disconnect from a TraceSource a Callback previously connected without a context. More...

Static Public Member Functions
static TypeId	GetTypeId ()
	Register this type. More...

Static Public Member Functions inherited from ns3::RandomVariableStream
static TypeId	GetTypeId ()
	Register this type. More...

Static Public Member Functions inherited from ns3::Object
static TypeId	GetTypeId ()
	Register this type. More...

Static Public Member Functions inherited from ns3::ObjectBase
static TypeId	GetTypeId ()
	Get the type ID. More...

Private Attributes
double	m_probability
	The probability of success in each trial. More...

uint32_t	m_trials
	The number of trials. More...

Additional Inherited Members
Protected Member Functions inherited from ns3::RandomVariableStream
RngStream *	Peek () const
	Get the pointer to the underlying RngStream. More...

Protected Member Functions inherited from ns3::Object
	Object (const Object &o)
	Copy an Object. More...

virtual void	DoDispose ()
	Destructor implementation. More...

virtual void	DoInitialize ()
	Initialize() implementation. More...

virtual void	NotifyNewAggregate ()
	Notify all Objects aggregated to this one of a new Object being aggregated. More...

Protected Member Functions inherited from ns3::ObjectBase
void	ConstructSelf (const AttributeConstructionList &attributes)
	Complete construction of ObjectBase; invoked by derived classes. More...

virtual void	NotifyConstructionCompleted ()
	Notifier called once the ObjectBase is fully constructed. More...

Related Functions inherited from ns3::ObjectBase
static TypeId	GetObjectIid ()
	Ensure the TypeId for ObjectBase gets fully configured to anchor the inheritance tree properly. More...

Detailed Description

The binomial distribution Random Number Generator (RNG).

This class supports the creation of objects that return random numbers from a fixed binomial distribution. It also supports the generation of single random numbers from various binomial distributions.

The probability mass function of a binomial variable is defined as:

$P(k; n, p) = \binom{n}{k} p^k (1-p)^{n-k}, \\ \quad k \in [0, n]$

where is the number of trials and is the probability of success in each trial. The mean of this distribution is $\mu = np$ and the variance is $\sigma^2 = np(1-p)$ .

The Binomial RNG value for a given number of trials and success probability is generated by

$k = \sum_{i=1}^{n} I(u_i \leq p)$

where is a uniform random variable on [0,1) for each trial, and is an indicator function that is 1 if $u_i \leq p$ and 0 otherwise. The sum of these indicator functions over all trials gives the total number of successes, which is the value of the binomial random variable.

Example

Here is an example of how to use this class:

uint32_t trials = 10;
double probability = 0.5;
 
Ptr<BinomialRandomVariable> x = CreateObject<BinomialRandomVariable> ();
x->SetAttribute ("Trials", UintegerValue (trials));
x->SetAttribute ("Probability", DoubleValue (probability));
 
double successes = x->GetValue ();

Antithetic Values.

If an instance of this RNG is configured to return antithetic values, the actual value returned, , for the Binomial process is determined by:

$k' = \sum_{i=1}^{n} I((1 - u_i) \leq p)$

where is a uniform random variable on [0,1) for each trial. The antithetic approach uses instead of in the indicator function.

Efficiency and Alternative Methods

There are alternative methods for generating binomial distributions that may offer greater efficiency. However, this implementation opts for a simpler approach. Although not as efficient, this method was chosen for its simplicity and sufficiency in most applications.

Definition at line 2142 of file random-variable-stream.h.

Constructor & Destructor Documentation

◆ BinomialRandomVariable()

ns3::BinomialRandomVariable::BinomialRandomVariable ( )

Definition at line 1764 of file random-variable-stream.cc.

References NS_LOG_FUNCTION.

Member Function Documentation

◆ GetInteger() [1/2]

uint32_t ns3::RandomVariableStream::GetInteger

virtual

Get the next random value drawn from the distribution.

Returns: A random value.

Reimplemented from ns3::RandomVariableStream.

Definition at line 155 of file random-variable-stream.cc.

◆ GetInteger() [2/2]

uint32_t ns3::BinomialRandomVariable::GetInteger	(	uint32_t	trials,
		uint32_t	probability
	)

Get the next random value drawn from the distribution.

Returns: A random value.

Parameters

[in]	trials	Number of trials.
[in]	probability	Probability of success in each trial.

Returns: Returns a number within the range [0, trials] indicating the number of successful trials. This function is similar to GetValue(), but it returns a uint32_t instead of a double.

Definition at line 1795 of file random-variable-stream.cc.

References GetValue(), and NS_LOG_FUNCTION.

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