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A Discrete-Event Network Simulator
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API |
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A Discrete-Event Network Simulator
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API |
The exponential distribution Random Number Generator (RNG). More...
#include "random-variable-stream.h"
Inheritance diagram for ns3::ExponentialRandomVariable:Public Member Functions | |
| ExponentialRandomVariable () | |
| Creates an exponential distribution RNG with the default values for the mean and upper bound. More... | |
| double | GetBound (void) const |
| Get the configured upper bound of this RNG. More... | |
| uint32_t | GetInteger (uint32_t mean, uint32_t bound) |
| Get the next random value, as an unsigned integer from the exponential distribution with the specified mean and upper bound. More... | |
| virtual uint32_t | GetInteger (void) |
| Get the next random value as an integer drawn from the distribution. More... | |
| double | GetMean (void) const |
| Get the configured mean value of this RNG. More... | |
| double | GetValue (double mean, double bound) |
| Get the next random value, as a double from the exponential distribution with the specified mean and upper bound. More... | |
| virtual double | GetValue (void) |
| Get the next random value as a double drawn from the distribution. More... | |
| Public Member Functions inherited from ns3::RandomVariableStream | |
| RandomVariableStream () | |
| Default constructor. More... | |
| virtual | ~RandomVariableStream () |
| Destructor. More... | |
| int64_t | GetStream (void) const |
| Returns the stream number for the RngStream. More... | |
| bool | IsAntithetic (void) const |
| Check if antithetic values will be generated. More... | |
| 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... | |
| virtual | ~Object () |
| Destructor. More... | |
| void | AggregateObject (Ptr< Object > other) |
| Aggregate two Objects together. More... | |
| void | Dispose (void) |
| Dispose of this Object. More... | |
| AggregateIterator | GetAggregateIterator (void) const |
| Get an iterator to the Objects aggregated to this one. More... | |
| virtual TypeId | GetInstanceTypeId (void) const |
| Get the most derived TypeId for this Object. More... | |
| template<typename T > | |
| Ptr< T > | GetObject (void) const |
| Get a pointer to the requested aggregated Object. More... | |
| template<typename T > | |
| Ptr< T > | GetObject (TypeId tid) const |
| Get a pointer to the requested aggregated Object by TypeId. More... | |
| void | Initialize (void) |
| Invoke DoInitialize on all Objects aggregated to this one. More... | |
| bool | IsInitialized (void) 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) | |
| Copy constructor. More... | |
| uint32_t | GetReferenceCount (void) const |
| Get the reference count of the object. More... | |
| SimpleRefCount & | operator= (const SimpleRefCount &o) |
| Assignment operator. More... | |
| void | Ref (void) const |
| Increment the reference count. More... | |
| void | Unref (void) 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 erros. 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 (void) |
| Register this type. More... | |
| Static Public Member Functions inherited from ns3::RandomVariableStream | |
| static TypeId | GetTypeId (void) |
| Register this type. More... | |
| Static Public Member Functions inherited from ns3::Object | |
| static TypeId | GetTypeId (void) |
| Register this type. More... | |
| Static Public Member Functions inherited from ns3::ObjectBase | |
| static TypeId | GetTypeId (void) |
| Get the type ID. More... | |
Private Attributes | |
| double | m_bound |
| The upper bound on values that can be returned by this RNG stream. More... | |
| double | m_mean |
| The mean value of the unbounded exponential distribution. More... | |
Additional Inherited Members | |
| Protected Member Functions inherited from ns3::RandomVariableStream | |
| RngStream * | Peek (void) 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 (void) |
| Destructor implementation. More... | |
| virtual void | DoInitialize (void) |
| Initialize() implementation. More... | |
| virtual void | NotifyNewAggregate (void) |
| 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 (void) |
| Notifier called once the ObjectBase is fully constructed. More... | |
| Related Functions inherited from ns3::ObjectBase | |
| static TypeId | GetObjectIid (void) |
| Ensure the TypeId for ObjectBase gets fully configured to anchor the inheritance tree properly. More... | |
The exponential distribution Random Number Generator (RNG).
This class supports the creation of objects that return random numbers from a fixed exponential distribution. It also supports the generation of single random numbers from various exponential distributions.
The probability density function of an exponential variable is defined as:
![\[ P(x) dx = \alpha e^{-\alpha x} dx, \quad x \in [0, +\infty) \]](form_9.png)
over the interval 
, where 
and Mean is a configurable attribute.
The normal RNG value 
is calculated by
![\[ x = - 1/\alpha \log(u) \]](form_12.png)
where 
is a uniform random variable on 
.
Since exponential distributions can theoretically return unbounded values, it is sometimes useful to specify a fixed upper limit. The bounded version is defined over the interval ![$[0,b]$](form_15.png)
as:
![\[ P(x; b) dx = \alpha e^{-\alpha x} dx \quad x \in [0,b] \]](form_16.png)
where the Bound 
is a configurable attribute.
Note that in this case the true mean of the distribution is smaller than the nominal mean value:
![\[ <X: P(x; b)> = 1/\alpha - b/(e^{\alpha \, b} -1) \]](form_18.png)
Here is an example of how to use this class:
The antithetic value is calculated from
![\[ x' = - mean * \log(1 - u), \]](form_19.png)
where again is a uniform random variable on .
ns3::ExponentialRandomVariable is accessible through the following paths with Config::Set and Config::Connect:
No TraceSources are defined for this type.
Size of this type is 72 bytes (on a 64-bit architecture).
Definition at line 538 of file random-variable-stream.h.
| ns3::ExponentialRandomVariable::ExponentialRandomVariable | ( | ) |
Creates an exponential distribution RNG with the default values for the mean and upper bound.
Definition at line 387 of file random-variable-stream.cc.
References NS_LOG_FUNCTION.
| double ns3::ExponentialRandomVariable::GetBound | ( | void | ) | const |
Get the configured upper bound of this RNG.
Definition at line 400 of file random-variable-stream.cc.
References m_bound, and NS_LOG_FUNCTION.
| uint32_t ns3::ExponentialRandomVariable::GetInteger | ( | uint32_t | mean, |
| uint32_t | bound | ||
| ) |
Get the next random value, as an unsigned integer from the exponential distribution with the specified mean and upper bound.
| [in] | mean | Mean value of the unbounded exponential distribution. |
| [in] | bound | Upper bound on values returned. |
Definition at line 430 of file random-variable-stream.cc.
References GetValue(), and NS_LOG_FUNCTION.
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virtual |
Get the next random value as an integer drawn from the distribution.
Implements ns3::RandomVariableStream.
Definition at line 443 of file random-variable-stream.cc.
References GetValue(), m_bound, m_mean, and NS_LOG_FUNCTION.
| double ns3::ExponentialRandomVariable::GetMean | ( | void | ) | const |
Get the configured mean value of this RNG.
Definition at line 394 of file random-variable-stream.cc.
References m_mean, and NS_LOG_FUNCTION.
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static |
Register this type.
Definition at line 370 of file random-variable-stream.cc.
References m_bound, m_mean, ns3::MakeDoubleAccessor(), and ns3::TypeId::SetParent().
| double ns3::ExponentialRandomVariable::GetValue | ( | double | mean, |
| double | bound | ||
| ) |
Get the next random value, as a double from the exponential distribution with the specified mean and upper bound.
| [in] | mean | Mean value of the unbounded exponential distribution. |
| [in] | bound | Upper bound on values returned. |
Definition at line 407 of file random-variable-stream.cc.
References ns3::RandomVariableStream::IsAntithetic(), NS_LOG_FUNCTION, ns3::RandomVariableStream::Peek(), and ns3::RngStream::RandU01().
Referenced by ns3::UanMacRc::Associate(), ns3::UanMacRc::AssociateTimeout(), RngExponentialTestCase::ChiSquaredTest(), RandomVariableStreamExponentialTestCase::ChiSquaredTest(), RandomVariableStreamExponentialAntitheticTestCase::ChiSquaredTest(), ns3::ThreeGppHttpVariables::GetParsingTime(), ns3::ThreeGppHttpVariables::GetReadingTime(), ns3::UanMacRc::RtsTimeout(), ns3::UanMacRc::ScheduleData(), Experiment::SendMultiDestinations(), and ns3::UanMacRc::SendRts().
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virtual |
Get the next random value as a double drawn from the distribution.
Implements ns3::RandomVariableStream.
Definition at line 437 of file random-variable-stream.cc.
References m_bound, m_mean, and NS_LOG_FUNCTION.
Referenced by GetInteger().
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private |
The upper bound on values that can be returned by this RNG stream.
Definition at line 595 of file random-variable-stream.h.
Referenced by GetBound(), GetInteger(), GetTypeId(), and GetValue().
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private |
The mean value of the unbounded exponential distribution.
Definition at line 592 of file random-variable-stream.h.
Referenced by GetInteger(), GetMean(), GetTypeId(), and GetValue().
1.8.14
