fern.tools

Class Stochastics

java.lang.Object

fern.tools.Stochastics

public class Stochastics
extends Object

Manages a random number generators for various distributions. By only using this class for every random number drawing in the whole framework, some advantages emerge:

• it is guaranteed that the most quickest possible generator is used for each drawing
• one can derandomize the algorithms by using setSeed(Date)
• the number of random number generations can easily be counted

Author:

Florian Erhard

Method Summary

Modifier and Type	Method and Description
int	getBinom(int i, double prob) Gets a random number from the binomial distribution.
int[]	getCounts() Gets the number of random number generations for each distribution (same order as in getNames() since the last call of resetCounts.
double	getExponential(double d) Gets a random number from the exponential distribution.
static Stochastics	getInstance() Singleton pattern method.
String[]	getNames() Gets the names of the built-in distributions.
double	getNormal() Gets a random number from the Normal distribution
double	getNormal(double mean, double stddev) Gets a random number from the Normal distribution with given mean and stddev.
int	getPoisson(double mean) Gets a random number from the Poisson distribution.
long	getSeed() Gets the actual seed of the random number generator.
double	getUnif() Gets a random number from the uniform distribution between 0 and 1.
int	getUnif(int min, int max) Gets a uniformly chosen random number between min (inclusive) and max (exclusive)
boolean	isCountGenerations() Gets whether or not to count the number of random number generations
void	resetCounts() Resets the counts for each distribution to zero.
void	resetSeed() Sets the seed to the current date
void	setCountGenerations(boolean countGenerations) Sets whether or not to count the number of random number generations
void	setSeed(Date seed) Sets a new seed for the random number generator.
void	setSeed(long seed) Sets a new seed for the random number generator.

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method Detail

getInstance

public static Stochastics getInstance()

Singleton pattern method.

Returns:

the singleton object

resetSeed

public void resetSeed()

Sets the seed to the current date

getSeed

public long getSeed()

Gets the actual seed of the random number generator.

Returns:

seed

setSeed

public void setSeed(long seed)

Sets a new seed for the random number generator.

Parameters:

seed - the seed

setSeed

public void setSeed(Date seed)

Sets a new seed for the random number generator.

Parameters:

seed - the seed

isCountGenerations

public boolean isCountGenerations()

Gets whether or not to count the number of random number generations

Returns:

whether or not to count

setCountGenerations

public void setCountGenerations(boolean countGenerations)

Sets whether or not to count the number of random number generations

Parameters:

countGenerations - whether or not to count

getCounts

public int[] getCounts()

Gets the number of random number generations for each distribution (same order as in getNames() since the last call of resetCounts.

Returns:

number of random number generations

getNames

public String[] getNames()

Gets the names of the built-in distributions.

Returns:

names of the distributions

resetCounts

public void resetCounts()

Resets the counts for each distribution to zero.

getUnif

public double getUnif()

Gets a random number from the uniform distribution between 0 and 1.

Returns:

random number between 0 and 1

See Also:

Uniform.nextDouble()

getExponential

public double getExponential(double d)

Gets a random number from the exponential distribution.

Parameters:

d - mean

Returns:

random number

See Also:

Exponential.nextDouble()

getBinom

public int getBinom(int i,
                    double prob)

Gets a random number from the binomial distribution.

Parameters:

i - size

prob - probability

Returns:

random number

See Also:

Binomial.nextInt(int, double)

getUnif

public int getUnif(int min,
                   int max)

Gets a uniformly chosen random number between min (inclusive) and max (exclusive)

Parameters:

min - inclusive minimum

max - exclusive maximum

Returns:

uniformly chosen random number

See Also:

Uniform.nextIntFromTo(int, int)

getPoisson

public int getPoisson(double mean)

Gets a random number from the Poisson distribution.

Parameters:

mean - mean

Returns:

random number

See Also:

Poisson.nextInt(double)

getNormal

public double getNormal()

Gets a random number from the Normal distribution

Returns:

random number

See Also:

Normal.nextDouble()

getNormal

public double getNormal(double mean,
                        double stddev)

Gets a random number from the Normal distribution with given mean and stddev.

Parameters:

mean - the mean

stddev - the stddev

Returns:

random number

See Also:

Normal.nextDouble(double, double)