RWTRandGamma< Generator > Class Template Reference
[Statistics]

Used to generate random numbers from a gamma distribution. More...

#include <rw/rand.h>

Inheritance diagram for RWTRandGamma< Generator >:

List of all members.

Public Member Functions
	RWTRandGamma (int ord=1)
	RWTRandGamma (const RWTRandGamma< Generator > &g)
	RWTRandGamma (const Generator &g, int ord=1)
virtual double	operator() ()
virtual size_t	operator() (double *out, size_t n)
void	setOrder (int order)
int	order () const

---

Detailed Description

template<class Generator>
class RWTRandGamma< Generator >

Class RWTRandGamma<Generator> generates random numbers from a gamma distribution:

where a is the order. The algorithm used to generate the random numbers begins with random numbers generated from a uniform distribution on the interval [0, 1]. Thus, the speed and statistical properties of the gamma random number generator may be varied by varying the Generator template parameter, which is responsible for generating the uniformly distributed numbers.

The class Generator must be a function object whose function call operator returns a uniform random double between 0 and 1. The class RWRandGenerator supplied with the library may be used.

Synopsis

 #include <rw/rand.h>
 RWTRandGamma<Generator> gen;

Examples

 #include <rw/rand.h>
 #include <iostream.h>
 #include "myrand.h"
 
 int main()  {
 // Create a uniform generator on [0, 1] with an
 // initial seed value.
   RWRandGenerator uniform(123456L);
 
 // Create a gamma generator with order = 4
 // using the above uniform generator for generator.
   RWTRandGamma<RWRandGenerator> gamma(uniform, 4);
 
 // Create an exponetial generator with order = 1 
 // using class RWRandGenerator.
   RWTRandGamma<RWRandGenerator> gammaOne;
 
 // Create a gamma generator with order 31 using a class
 // MyDoubleRand to generate the uniform [0, 1] deviates.
   RWTRandGamma<MyDoubleRand> myGamma(31);
 
 // Print a few values.
   for ( int j = 0; j < 10; j++ )
   {
     cout << "gamma order = 4 = " << gamma();
     cout << "\ngamma order = 1 = " << gammaOne();
     cout << "\ngamma order = 31 = " << myGamma() << endl;
 }
   
 // Restart one of the generators with another seed value
 // using the RWRandGenerator method restart().
   ( gammaOne.generator() ).restart( 654321L);
 
   return 0;
 }

---

Constructor & Destructor Documentation

template<class Generator>

RWTRandGamma< Generator >::RWTRandGamma

(

int

ord = 1

)

Constructs a generator with order = ord.

template<class Generator>

RWTRandGamma< Generator >::RWTRandGamma

(

const RWTRandGamma< Generator > &

g

)

Constructs self as a copy of g.

template<class Generator>

RWTRandGamma< Generator >::RWTRandGamma	(	const Generator &	g,
		int	ord = 1
	)

Constructs a generator with underlying uniform [0, 1] generator g order = ord.

---

Member Function Documentation

template<class Generator>

virtual size_t RWTRandGamma< Generator >::operator()	(	double *	out,
		size_t	n
	)			[virtual]

Assigns random numbers to n elements in out. Returns the number of random numbers generated.

Implements RWRandInterface.

template<class Generator>

virtual double RWTRandGamma< Generator >::operator()

(

)

[virtual]

Returns the next random number in the sequence.

Implements RWRandInterface.

template<class Generator>

int RWTRandGamma< Generator >::order

(

)

const [inline]

Returns the value of order for the distribution.

template<class Generator>

void RWTRandGamma< Generator >::setOrder

(

int

order

)

[inline]

Sets the value of lamda for the distribution to l.