A Discrete-Event Network Simulator
API
Loading...
Searching...
No Matches
Public Member Functions | Static Public Member Functions | Private Attributes | List of all members
ns3::BinomialRandomVariable Class Reference
Core » Random Variables

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.
 
uint32_t GetInteger (uint32_t trials, uint32_t probability)
 Get the next random value drawn from the distribution.
 
double GetValue () override
 Get the next random value drawn from the distribution.
 
double GetValue (uint32_t trials, double probability)
 Get the next random value drawn from the distribution.
 
- Public Member Functions inherited from ns3::RandomVariableStream
 RandomVariableStream ()
 Default constructor.
 
 RandomVariableStream (const RandomVariableStream &)=delete
 
 ~RandomVariableStream () override
 Destructor.
 
int64_t GetStream () const
 Returns the stream number for the RngStream.
 
bool IsAntithetic () const
 Check if antithetic values will be generated.
 
RandomVariableStream & operator= (const RandomVariableStream &)=delete
 
void SetAntithetic (bool isAntithetic)
 Specify whether antithetic values should be generated.
 
void SetStream (int64_t stream)
 Specifies the stream number for the RngStream.
 
- Public Member Functions inherited from ns3::Object
 Object ()
 Constructor.
 
 ~Object () override
 Destructor.
 
void AggregateObject (Ptr< Object > other)
 Aggregate two Objects together.
 
void Dispose ()
 Dispose of this Object.
 
AggregateIterator GetAggregateIterator () const
 Get an iterator to the Objects aggregated to this one.
 
TypeId GetInstanceTypeId () const override
 Get the most derived TypeId for this Object.
 
template<typename T >
Ptr< T > GetObject () const
 Get a pointer to the requested aggregated Object.
 
template<>
Ptr< Object > GetObject () const
 Specialization of () for objects of type ns3::Object.
 
template<typename T >
Ptr< T > GetObject (TypeId tid) const
 Get a pointer to the requested aggregated Object by TypeId.
 
template<>
Ptr< Object > GetObject (TypeId tid) const
 Specialization of (TypeId tid) for objects of type ns3::Object.
 
void Initialize ()
 Invoke DoInitialize on all Objects aggregated to this one.
 
bool IsInitialized () const
 Check if the object has been initialized.
 
void UnidirectionalAggregateObject (Ptr< Object > other)
 Aggregate an Object to another Object.
 
- Public Member Functions inherited from ns3::SimpleRefCount< Object, ObjectBase, ObjectDeleter >
 SimpleRefCount ()
 Default constructor.
 
 SimpleRefCount (const SimpleRefCount &o)
 Copy constructor.
 
uint32_t GetReferenceCount () const
 Get the reference count of the object.
 
SimpleRefCount & operator= (const SimpleRefCount &o)
 Assignment operator.
 
void Ref () const
 Increment the reference count.
 
void Unref () const
 Decrement the reference count.
 
- Public Member Functions inherited from ns3::ObjectBase
virtual ~ObjectBase ()
 Virtual destructor.
 
void GetAttribute (std::string name, AttributeValue &value, bool permissive=false) const
 Get the value of an attribute, raising fatal errors if unsuccessful.
 
bool GetAttributeFailSafe (std::string name, AttributeValue &value) const
 Get the value of an attribute without raising errors.
 
void SetAttribute (std::string name, const AttributeValue &value)
 Set a single attribute, raising fatal errors if unsuccessful.
 
bool SetAttributeFailSafe (std::string name, const AttributeValue &value)
 Set a single attribute without raising errors.
 
bool TraceConnect (std::string name, std::string context, const CallbackBase &cb)
 Connect a TraceSource to a Callback with a context.
 
bool TraceConnectWithoutContext (std::string name, const CallbackBase &cb)
 Connect a TraceSource to a Callback without a context.
 
bool TraceDisconnect (std::string name, std::string context, const CallbackBase &cb)
 Disconnect from a TraceSource a Callback previously connected with a context.
 
bool TraceDisconnectWithoutContext (std::string name, const CallbackBase &cb)
 Disconnect from a TraceSource a Callback previously connected without a context.
 

Static Public Member Functions

static TypeId GetTypeId ()
 Register this type.
 
- Static Public Member Functions inherited from ns3::RandomVariableStream
static TypeId GetTypeId ()
 Register this type.
 
- Static Public Member Functions inherited from ns3::Object
static TypeId GetTypeId ()
 Register this type.
 
- Static Public Member Functions inherited from ns3::ObjectBase
static TypeId GetTypeId ()
 Get the type ID.
 

Private Attributes

double m_probability
 The probability of success in each trial.
 
uint32_t m_trials
 The number of trials.
 

Additional Inherited Members

- Protected Member Functions inherited from ns3::RandomVariableStream
RngStream * Peek () const
 Get the pointer to the underlying RngStream.
 
- Protected Member Functions inherited from ns3::Object
 Object (const Object &o)
 Copy an Object.
 
virtual void DoDispose ()
 Destructor implementation.
 
virtual void DoInitialize ()
 Initialize() implementation.
 
virtual void NotifyNewAggregate ()
 Notify all Objects aggregated to this one of a new Object being aggregated.
 
- Protected Member Functions inherited from ns3::ObjectBase
void ConstructSelf (const AttributeConstructionList &attributes)
 Complete construction of ObjectBase; invoked by derived classes.
 
virtual void NotifyConstructionCompleted ()
 Notifier called once the ObjectBase is fully constructed.
 
- Related Symbols inherited from ns3::ObjectBase
 Ensure the TypeId for ObjectBase gets fully configured to anchor the inheritance tree properly.
 

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 $ n $ is the number of trials and $ p $ 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 $n$ for a given number of trials $ n $ and success probability $ p $ is generated by

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

where $u_i$ is a uniform random variable on [0,1) for each trial, and $I$ 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 ();
ns3::DoubleValue
This class can be used to hold variables of floating point type such as 'double' or 'float'.
Definition double.h:31
ns3::Ptr
Smart pointer class similar to boost::intrusive_ptr.
Definition mpi-test-fixtures.h:37
ns3::UintegerValue
Hold an unsigned integer type.
Definition uinteger.h:34
uint32_t
ns3::CreateObject
Ptr< T > CreateObject(Args &&... args)
Create an object by type, with varying number of constructor parameters.
Definition object.h:619
Antithetic Values.

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

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

where $u_i$ is a uniform random variable on [0,1) for each trial. The antithetic approach uses $(1 - u_i)$ instead of $u_i$ 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 2144 of file random-variable-stream.h.

Constructor & Destructor Documentation

◆ BinomialRandomVariable()

ns3::BinomialRandomVariable::BinomialRandomVariable ( )

Definition at line 1762 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 144 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]trialsNumber of trials.
[in]probabilityProbability 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 1792 of file random-variable-stream.cc.

References ns3::RandomVariableStream::GetStream(), GetValue(), and NS_LOG_DEBUG.

+ Here is the call graph for this function:

◆ GetTypeId()

TypeId ns3::BinomialRandomVariable::GetTypeId ( )
static

Register this type.

Returns
The object TypeId.

Definition at line 1742 of file random-variable-stream.cc.

References m_probability, m_trials, ns3::MakeDoubleAccessor(), ns3::MakeDoubleChecker(), ns3::MakeIntegerAccessor(), ns3::MakeIntegerChecker(), and ns3::TypeId::SetParent().

+ Here is the call graph for this function:

◆ GetValue() [1/2]

double ns3::BinomialRandomVariable::GetValue ( )
overridevirtual

Get the next random value drawn from the distribution.

Returns
A random value.

Implements ns3::RandomVariableStream.

Definition at line 1801 of file random-variable-stream.cc.

References GetValue(), m_probability, and m_trials.

Referenced by GetInteger(), and GetValue().

+ Here is the call graph for this function:
+ Here is the caller graph for this function:

◆ GetValue() [2/2]

double ns3::BinomialRandomVariable::GetValue ( uint32_t trials,
double probability )

Get the next random value drawn from the distribution.

Returns
A random value.
Parameters
[in]trialsNumber of trials.
[in]probabilityProbability of success in each trial.
Returns
Returns a number within the range [0, trials] indicating the number of successful trials.

Definition at line 1769 of file random-variable-stream.cc.

References ns3::RandomVariableStream::GetStream(), ns3::RandomVariableStream::IsAntithetic(), NS_LOG_DEBUG, ns3::RandomVariableStream::Peek(), and ns3::RngStream::RandU01().

+ Here is the call graph for this function:

Member Data Documentation

◆ m_probability

double ns3::BinomialRandomVariable::m_probability
private

The probability of success in each trial.

Definition at line 2179 of file random-variable-stream.h.

Referenced by GetTypeId(), and GetValue().

◆ m_trials

uint32_t ns3::BinomialRandomVariable::m_trials
private

The number of trials.

Definition at line 2176 of file random-variable-stream.h.

Referenced by GetTypeId(), and GetValue().

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