The gamma distribution Random Number Generator (RNG) that allows stream numbers to be set deterministically. More...
#include "random-variable-stream.h"
Public Member Functions | |
GammaRandomVariable () | |
Creates a gamma distribution RNG with the default values for alpha and beta. | |
double | GetAlpha () const |
Returns the alpha value for the gamma distribution returned by this RNG stream. | |
double | GetBeta () const |
Returns the beta value for the gamma distribution returned by this RNG stream. | |
virtual uint32_t | GetInteger () |
Get the next random value drawn from the distribution. | |
uint32_t | GetInteger (uint32_t alpha, uint32_t beta) |
Get the next random value drawn from the distribution. | |
double | GetValue () override |
Get the next random value drawn from the distribution. | |
double | GetValue (double alpha, double beta) |
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 Member Functions | |
double | GetNormalValue (double mean, double variance, double bound) |
Returns a random double from a normal distribution with the specified mean, variance, and bound. | |
Private Attributes | |
double | m_alpha |
The alpha value for the gamma distribution returned by this RNG stream. | |
double | m_beta |
The beta value for the gamma distribution returned by this RNG stream. | |
bool | m_nextValid |
True if the next normal value is valid. | |
double | m_v2 |
The algorithm produces two values at a time. | |
double | m_y |
The algorithm produces two values at a time. | |
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 | |
static TypeId | GetObjectIid () |
Ensure the TypeId for ObjectBase gets fully configured to anchor the inheritance tree properly. | |
The gamma distribution Random Number Generator (RNG) that allows stream numbers to be set deterministically.
This class supports the creation of objects that return random numbers from a fixed gamma distribution. It also supports the generation of single random numbers from various gamma distributions.
The probability distribution is defined in terms two parameters, Alpha
= and Beta
= . (Note the Wikipedia entry for the Gamma Distribution uses either the parameters or . The parameters used here correspond to .)
The probability density function is:
where the mean is and the variance is .
While gamma RNG values can be generated by an algorithm similar to normal RNGs, the implementation used here is based on the paper G. Marsaglia and W. W. Tsang, A simple method for generating Gamma variables, ACM Transactions on Mathematical Software, Vol. 26, No. 3, Sept. 2000.
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 using the prescription in the Marsaglia, et al. paper cited above.
ns3::GammaRandomVariable is accessible through the following paths with Config::Set and Config::Connect:
No TraceSources are defined for this type.
Group: Core
Size of this type is 120 bytes (on a 64-bit architecture).
Definition at line 1247 of file random-variable-stream.h.
ns3::GammaRandomVariable::GammaRandomVariable | ( | ) |
Creates a gamma distribution RNG with the default values for alpha and beta.
Definition at line 927 of file random-variable-stream.cc.
References NS_LOG_FUNCTION.
double ns3::GammaRandomVariable::GetAlpha | ( | ) | const |
Returns the alpha value for the gamma distribution returned by this RNG stream.
Definition at line 936 of file random-variable-stream.cc.
References m_alpha.
double ns3::GammaRandomVariable::GetBeta | ( | ) | const |
Returns the beta value for the gamma distribution returned by this RNG stream.
Definition at line 942 of file random-variable-stream.cc.
References m_beta.
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virtual |
Get the next random value drawn from the distribution.
Reimplemented from ns3::RandomVariableStream.
Definition at line 144 of file random-variable-stream.cc.
Get the next random value drawn from the distribution.
[in] | alpha | Alpha value for the gamma distribution. |
[in] | beta | Beta value for the gamma distribution. |
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private |
Returns a random double from a normal distribution with the specified mean, variance, and bound.
[in] | mean | Mean value for the normal distribution. |
[in] | variance | Variance value for the normal distribution. |
[in] | bound | Bound on values returned. |
Definition at line 1028 of file random-variable-stream.cc.
References ns3::RandomVariableStream::GetStream(), ns3::RandomVariableStream::IsAntithetic(), m_nextValid, m_v2, m_y, NS_LOG_DEBUG, ns3::RandomVariableStream::Peek(), and ns3::RngStream::RandU01().
Referenced by GetValue().
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static |
Register this type.
Definition at line 907 of file random-variable-stream.cc.
References m_alpha, m_beta, ns3::MakeDoubleAccessor(), ns3::MakeDoubleChecker(), and ns3::TypeId::SetParent().
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overridevirtual |
Get the next random value drawn from the distribution.
Implements ns3::RandomVariableStream.
Definition at line 1022 of file random-variable-stream.cc.
References GetValue(), m_alpha, and m_beta.
Referenced by GetValue(), and GetValue().
Get the next random value drawn from the distribution.
[in] | alpha | Alpha value for the gamma distribution. |
[in] | beta | Beta value for the gamma distribution. |
Definition at line 964 of file random-variable-stream.cc.
References GetNormalValue(), ns3::RandomVariableStream::GetStream(), GetValue(), ns3::NormalRandomVariable::INFINITE_VALUE, ns3::RandomVariableStream::IsAntithetic(), NS_LOG_DEBUG, ns3::RandomVariableStream::Peek(), and ns3::RngStream::RandU01().
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private |
The alpha value for the gamma distribution returned by this RNG stream.
Definition at line 1300 of file random-variable-stream.h.
Referenced by GetAlpha(), GetTypeId(), and GetValue().
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private |
The beta value for the gamma distribution returned by this RNG stream.
Definition at line 1303 of file random-variable-stream.h.
Referenced by GetBeta(), GetTypeId(), and GetValue().
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private |
True if the next normal value is valid.
Definition at line 1306 of file random-variable-stream.h.
Referenced by GetNormalValue().
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private |
The algorithm produces two values at a time.
Cache parameters for possible reuse.
Definition at line 1309 of file random-variable-stream.h.
Referenced by GetNormalValue().
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private |
The algorithm produces two values at a time.
Cache parameters for possible reuse.
Definition at line 1311 of file random-variable-stream.h.
Referenced by GetNormalValue().