RandomVariateGenWithCache Class Reference

This class represents a random variate generator whose values are cached for more efficiency when using common random numbers. More...

Inheritance diagram for RandomVariateGenWithCache:

Collaboration diagram for RandomVariateGenWithCache:

Public Member Functions
	RandomVariateGenWithCache (RandomVariateGen rvg)
	Constructs a new cached random variate generator with internal generator rvg. More...
	RandomVariateGenWithCache (RandomVariateGen rvg, int initialCapacity)
	Constructs a new cached random variate generator with internal generator rvg. More...
boolean	isCaching ()
	Determines if the random variate generator is caching values, default being true. More...
void	setCaching (boolean caching)
	Sets the caching indicator to caching. More...
RandomVariateGen	getCachedGen ()
	Returns a reference to the random variate generator whose values are cached. More...
void	setCachedGen (RandomVariateGen rvg)
	Sets the random variate generator whose values are cached to rvg. More...
void	clearCache ()
	Clears the cached values for this cached generator. More...
void	initCache ()
	Resets this generator to recover values from the cache. More...
int	getNumCachedValues ()
	Returns the total number of values cached by this generator. More...
int	getCacheIndex ()
	Return the index of the next cached value that will be returned by the generator. More...
void	setCacheIndex (int newIndex)
	Sets the index, in the cache, of the next value returned by #nextDouble. More...
DoubleArrayList	getCachedValues ()
	Returns an array list containing the values cached by this random variate generator. More...
void	setCachedValues (DoubleArrayList values)
	Sets the array list containing the cached values to values. More...
double	nextDouble ()
void	nextArrayOfDouble (double[] v, int start, int n)
RandomStream	getStream ()
Distribution	getDistribution ()
Public Member Functions inherited from RandomVariateGen
	RandomVariateGen (RandomStream s, Distribution dist)
	Creates a new random variate generator from the distribution dist, using stream s. More...
double	nextDouble ()
	Generates a random number from the continuous distribution contained in this object. More...
void	nextArrayOfDouble (double[] v, int start, int n)
	Generates n random numbers from the continuous distribution contained in this object. More...
double []	nextArrayOfDouble (int n)
	Generates n random numbers from the continuous distribution contained in this object, and returns them in a new array of size n. More...
RandomStream	getStream ()
	Returns the umontreal.ssj.rng.RandomStream used by this generator. More...
void	setStream (RandomStream stream)
	Sets the umontreal.ssj.rng.RandomStream used by this generator to stream.
Distribution	getDistribution ()
	Returns the umontreal.ssj.probdist.Distribution used by this generator. More...
String	toString ()
	Returns a String containing information about the current generator.

Additional Inherited Members
Protected Attributes inherited from RandomVariateGen
RandomStream	stream
Distribution	dist

Detailed Description

This class represents a random variate generator whose values are cached for more efficiency when using common random numbers.

An object from this class is constructed with a reference to a RandomVariateGen instance used to get the random numbers. These numbers are stored in an internal array to be retrieved later. The dimension of the array increases as the values are generated. If the #nextDouble method is called after the object is reset (by calling setCachedValues(DoubleArrayList) ), it gives back the cached values instead of computing new ones. If the cache is exhausted before the generator is reset, new values are computed and added to the cache.

Such caching allows for a better performance with common random numbers, when generating random variates is time-consuming. However, using such caching may lead to memory problems if a large quantity of random numbers are needed.

Constructor & Destructor Documentation

RandomVariateGenWithCache() [1/2]

RandomVariateGenWithCache

(

RandomVariateGen

rvg

)

Constructs a new cached random variate generator with internal generator rvg.

Parameters

rvg	the random variate generator whose values are cached.

Exceptions

NullPointerException

if rvg is null.

RandomVariateGenWithCache() [2/2]

RandomVariateGenWithCache	(	RandomVariateGen	rvg,
		int	initialCapacity
	)

Constructs a new cached random variate generator with internal generator rvg.

The initialCapacity parameter is used to set the initial capacity of the internal array which can grow as needed; it does not limit the maximal number of cached values.

Parameters

rvg	the random variate generator whose values are cached.
initialCapacity	the number of cached values.

Exceptions

NullPointerException

if rvg is null.

Member Function Documentation

clearCache()

void clearCache

(

)

Clears the cached values for this cached generator.

Any subsequent call will then obtain new values from the internal generator.

getCachedGen()

RandomVariateGen getCachedGen

(

)

Returns a reference to the random variate generator whose values are cached.

Returns

a reference to the random variate generator whose values are cached.

getCachedValues()

DoubleArrayList getCachedValues

(

)

Returns an array list containing the values cached by this random variate generator.

Returns

the array of cached values.

getCacheIndex()

int getCacheIndex

(

)

Return the index of the next cached value that will be returned by the generator.

If the cache is exhausted, the returned value corresponds to the value returned by getNumCachedValues, and a subsequent call to #nextDouble will generate a new variate rather than reading a previous one from the cache. If caching is disabled, this always returns 0.

Returns

the index of the next cached value.

getNumCachedValues()

int getNumCachedValues

(

)

Returns the total number of values cached by this generator.

Returns

the total number of cached values.

initCache()

void initCache

(

)

Resets this generator to recover values from the cache.

Subsequent calls to #nextDouble will return the cached random values until all the values are returned. When the array of cached values is exhausted, the internal random variate generator is used to generate new values which are added to the internal array as well. This method is equivalent to calling setCacheIndex(int).

isCaching()

boolean isCaching

(

)

Determines if the random variate generator is caching values, default being true.

When caching is turned OFF, the #nextDouble method simply calls the corresponding method on the internal random variate generator, without storing the generated values.

Returns

the caching indicator.

setCachedGen()

void setCachedGen

(

RandomVariateGen

rvg

)

Sets the random variate generator whose values are cached to rvg.

If the generator is changed, the clearCache method is called.

Parameters

rvg	the new random variate generator whose values are cached.

Exceptions

NullPointerException

if rvg is null.

setCachedValues()

void setCachedValues

(

DoubleArrayList

values

)

Sets the array list containing the cached values to values.

This resets the cache index to the size of the given array.

Parameters

values

the array list of cached values.

Exceptions

NullPointerException

if values is null.

setCacheIndex()

void setCacheIndex

(

int

newIndex

)

Sets the index, in the cache, of the next value returned by #nextDouble.

If newIndex is 0, this is equivalent to calling initCache. If newIndex is getNumCachedValues, subsequent calls to #nextDouble will add new values to the cache.

Parameters

newIndex

the new index.

Exceptions

IllegalArgumentException

if newIndex is negative or greater than or equal to the cache size.

setCaching()

void setCaching

(

boolean

caching

)

Sets the caching indicator to caching.

If caching is turned OFF, this method calls clearCache to clear the cached values.

Parameters

caching

the new value of the caching indicator.

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

• RandomVariateGenWithCache.java