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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 Weibull distribution Random Number Generator (RNG) which allows stream numbers to be set deterministically. More...
#include "random-variable-stream.h"
Inheritance diagram for ns3::WeibullRandomVariable: Collaboration diagram for ns3::WeibullRandomVariable:Public Member Functions | |
| WeibullRandomVariable () | |
| Creates a Weibull distribution RNG with the default values for the scale, shape, and upper bound. More... | |
| double | GetBound () const |
| Returns the upper bound on values that can be returned by this RNG stream. More... | |
| virtual uint32_t | GetInteger () |
| Get the next random value drawn from the distribution. More... | |
| uint32_t | GetInteger (uint32_t scale, uint32_t shape, uint32_t bound) |
| Get the next random value drawn from the distribution. More... | |
| double | GetScale () const |
| Returns the scale parameter for the Weibull distribution returned by this RNG stream. More... | |
| double | GetShape () const |
| Returns the shape parameter for the Weibull distribution returned by this RNG stream. More... | |
| double | GetValue () override |
| Get the next random value drawn from the distribution. More... | |
| double | GetValue (double scale, double shape, double bound) |
| 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_bound |
| The upper bound on values that can be returned by this RNG stream. More... | |
| double | m_scale |
| The scale parameter for the Weibull distribution returned by this RNG stream. More... | |
| double | m_shape |
| The shape parameter for the Weibull distribution returned by this RNG stream. 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... | |
The Weibull distribution Random Number Generator (RNG) which allows stream numbers to be set deterministically.
This class supports the creation of objects that return random numbers from a fixed Weibull distribution. It also supports the generation of single random numbers from various Weibull distributions.
The probability density function is:
![\[ P(x; \lambda, k) dx = \frac{k}{\lambda} \\ \left(\frac{x}{\lambda}\right)^{k-1} \\ e^{-\left(\frac{x}{\lambda}\right)^k} dx, \\ \quad x \in [0, +\infty) \]](../../form_37.png)
where 
is the Shape parameter and 
is the Scale parameter.
The mean 
is related to the Scale and Shape parameters by the following relation:
![\[ \mu = \lambda\Gamma\left(1+\frac{1}{k}\right) \]](../../form_40.png)
where 
is the Gamma function.
The variance of the distribution is
![\[ \sigma^2 = \lambda^2 \left[ \Gamma\left(1 + \frac{2}{k}\right) - \\ \left( \Gamma\left(1 + \frac{1}{k}\right)\right)^2 \right] \]](../../form_42.png)
For 
the mean rapidly approaches just 
, with variance
![\[ \sigma^2 \approx \frac{\pi^2}{6 k^2} + \mathcal{O}(k^{-3}) \]](../../form_45.png)
The Weibull RNG value 
is generated by
![\[ x = \lambda {(-\log(u))}^{\frac{1}{k}} \]](../../form_46.png)
where 
is a uniform random variable on [0,1).
Since Weibull distributions can theoretically return unbounded values, it is sometimes useful to specify a fixed upper limit. The bounded version is defined over the interval ![$ x \in [0, b] $](../../form_47.png)
. Note however when the upper limit is specified, the mean of the resulting distribution is slightly smaller than the mean value in the unbounded case.
Here is an example of how to use this class:
If an instance of this RNG is configured to return antithetic values, the actual value returned, 
, is generated as follows:
![\[ x' = \lambda {(-\log(1 - u))}^{\frac{1}{k}} , \]](../../form_48.png)
which now involves the log of the distance is from 1.
ns3::WeibullRandomVariable is accessible through the following paths with Config::Set and Config::Connect:
No TraceSources are defined for this type.
Size of this type is 80 bytes (on a 64-bit architecture).
Definition at line 830 of file random-variable-stream.h.
| ns3::WeibullRandomVariable::WeibullRandomVariable | ( | ) |
Creates a Weibull distribution RNG with the default values for the scale, shape, and upper bound.
Definition at line 587 of file random-variable-stream.cc.
References NS_LOG_FUNCTION.
| double ns3::WeibullRandomVariable::GetBound | ( | ) | const |
Returns the upper bound on values that can be returned by this RNG stream.
Definition at line 609 of file random-variable-stream.cc.
References m_bound, and NS_LOG_FUNCTION.
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virtual |
Get the next random value drawn from the distribution.
Reimplemented from ns3::RandomVariableStream.
Definition at line 153 of file random-variable-stream.cc.
| uint32_t ns3::WeibullRandomVariable::GetInteger | ( | uint32_t | scale, |
| uint32_t | shape, | ||
| uint32_t | bound | ||
| ) |
Get the next random value drawn from the distribution.
| [in] | scale | Scale parameter for the Weibull distribution. |
| [in] | shape | Shape parameter for the Weibull distribution. |
| [in] | bound | Upper bound on values returned. |
Definition at line 641 of file random-variable-stream.cc.
References GetValue(), and NS_LOG_FUNCTION.
Here is the call graph for this function:| double ns3::WeibullRandomVariable::GetScale | ( | ) | const |
Returns the scale parameter for the Weibull distribution returned by this RNG stream.
Definition at line 595 of file random-variable-stream.cc.
References m_scale, and NS_LOG_FUNCTION.
| double ns3::WeibullRandomVariable::GetShape | ( | ) | const |
Returns the shape parameter for the Weibull distribution returned by this RNG stream.
Definition at line 602 of file random-variable-stream.cc.
References m_shape, and NS_LOG_FUNCTION.
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static |
Register this type.
Definition at line 560 of file random-variable-stream.cc.
References m_bound, m_scale, m_shape, ns3::MakeDoubleAccessor(), and ns3::TypeId::SetParent().
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overridevirtual |
Get the next random value drawn from the distribution.
Implements ns3::RandomVariableStream.
Definition at line 648 of file random-variable-stream.cc.
References m_bound, m_scale, m_shape, and NS_LOG_FUNCTION.
Referenced by GetInteger().
Here is the caller graph for this function:| double ns3::WeibullRandomVariable::GetValue | ( | double | scale, |
| double | shape, | ||
| double | bound | ||
| ) |
Get the next random value drawn from the distribution.
| [in] | scale | Scale parameter for the Weibull distribution. |
| [in] | shape | Shape parameter for the Weibull distribution. |
| [in] | bound | Upper bound on values returned. |
Definition at line 616 of file random-variable-stream.cc.
References ns3::RandomVariableStream::IsAntithetic(), NS_LOG_FUNCTION, ns3::RandomVariableStream::Peek(), and ns3::RngStream::RandU01().
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private |
The upper bound on values that can be returned by this RNG stream.
Definition at line 886 of file random-variable-stream.h.
Referenced by GetBound(), GetTypeId(), and GetValue().
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private |
The scale parameter for the Weibull distribution returned by this RNG stream.
Definition at line 880 of file random-variable-stream.h.
Referenced by GetScale(), GetTypeId(), and GetValue().
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private |
The shape parameter for the Weibull distribution returned by this RNG stream.
Definition at line 883 of file random-variable-stream.h.
Referenced by GetShape(), GetTypeId(), and GetValue().
1.9.1 
