ns3::ErlangVariable Class Reference
[Random Variable Distributions]

Erlang Distributed Random Variable

ErlangVariable defines a random variable with Erlang distribution. More...

#include <random-variable.h>

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List of all members.

Public Member Functions

 ErlangVariable ()
 ErlangVariable (unsigned int k, double lambda)
double GetValue (void) const
 call RandomVariable::GetValue
double GetValue (unsigned int k, double lambda) const
 Returns an Erlang random distributed double with parameters k and lambda.


Detailed Description

Erlang Distributed Random Variable

ErlangVariable defines a random variable with Erlang distribution.

The Erlang distribution is a special case of the Gamma distribution where k (= alpha) is a non-negative integer. Erlang distributed variables can be generated using a much faster algorithm than gamma variables.

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

The probability density function is defined over the interval [0,+inf) as: $ \frac{x^{k-1} e^{-\frac{x}{\lambda}}}{\lambda^k (k-1)!}$ where $ mean = k \lambda $ and $ variance = k \lambda^2$


Constructor & Destructor Documentation

ns3::ErlangVariable::ErlangVariable (  ) 

Constructs an Erlang random variable with k = 1 and lambda = 1.0

ns3::ErlangVariable::ErlangVariable ( unsigned int  k,
double  lambda 
)

Parameters:
k k parameter of the Erlang distribution. Must be a non-negative integer.
lambda lambda parameter of the Erlang distribution


Member Function Documentation

double ns3::ErlangVariable::GetValue ( unsigned int  k,
double  lambda 
) const

Returns an Erlang random distributed double with parameters k and lambda.

Parameters:
k k parameter of the Erlang distribution. Must be a non-negative integer.
lambda lambda parameter of the Erlang distribution
Returns:
A floating point random value

double ns3::ErlangVariable::GetValue ( void   )  const

call RandomVariable::GetValue

Returns:
A floating point random value
Note: we have to re-implement this method here because the method is overloaded below for the two-argument variant and the c++ name resolution rules don't work well with overloads split between parent and child classes.

Reimplemented from ns3::RandomVariable.


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

Generated on Fri Apr 9 15:01:09 2010 for NS-3 by  doxygen 1.5.8