org.lcsim.recon.tracking.trfutil

Class RandomGenerator

java.lang.Object

org.lcsim.recon.tracking.trfutil.RandomGenerator

Direct Known Subclasses:

HitGenerator, HTrackGenerator, RandomGeneratorTest, SimInteractor, VTrackGenerator

public class RandomGenerator
extends Object

A generator produces objects with random parameters. This class is abstract and contains the interface for the random number generator. Each instance will maintain its own sequence of random numbers. We use the default Java random number generator. The calls to rand are encapsulated so that we can keep count of the number of calls to reproduce the state.

Version:

1.0

Author:

Norman A. Graf

Field Summary

Fields

Modifier and Type	Field and Description
private int	_ncall
private Random	_rand
private long	_seed

Constructor Summary

Constructors

Constructor and Description
RandomGenerator() Default constructor.
RandomGenerator(long seed) Constructor from seed.
RandomGenerator(RandomGenerator rgen) Copy constructor.

Method Summary

Methods

Modifier and Type	Method and Description
protected double	flat(double min, double max) Return a flat value in range (min.max).
protected double	gauss() Return a random number according to a Gaussian distribution with sigma = 1.0.
long	seed() Get the seed.
void	setSeed(long seed) Set the seed.
private void	setState(long seed, int ncall) Set the state = seed and number of calls.
void	setState(RandomGenerator rgen) Set the state (seed + ncall) to be the same as that of the argument.
String	toString() String representation of this RandomGenerator.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Field Detail

_rand

private Random _rand

_ncall

private int _ncall

_seed

private long _seed

Constructor Detail

RandomGenerator

public RandomGenerator()

Default constructor.

RandomGenerator

public RandomGenerator(long seed)

Constructor from seed.

Parameters:

seed - long value seeding the random number generator.

RandomGenerator

public RandomGenerator(RandomGenerator rgen)

Copy constructor. The new generator is independent from the original and is in the same state. Set the original seed and skip through the same number of values to obtain the same state.

Parameters:

rgen - The RandomGenerator to copy.

Method Detail

setState

private void setState(long seed,
            int ncall)

Set the state = seed and number of calls.

Parameters:

seed - Random number seed

ncall - Number of calls to this generator

flat

protected double flat(double min,
          double max)

Return a flat value in range (min.max).

Parameters:

min - The minimum of the range.

max - The maximum of the range.

Returns:

A double value flat between min and max .

gauss

protected double gauss()

Return a random number according to a Gaussian distribution with sigma = 1.0. We do it this way to ensure that we can reproduce the same sequence.

Returns:

A double value gaussian distributed with mean 0 and sigma 1.

setSeed

public void setSeed(long seed)

Set the seed. Generator is positioned at the beginning of the sequence. This reinitializes the generator engine, positioning it at the first value in the sequence.

Parameters:

seed - long value seeding the random number generator.

seed

public long seed()

Get the seed.

Returns:

long value which seeded this random number generator.

setState

public void setState(RandomGenerator rgen)

Set the state (seed + ncall) to be the same as that of the argument.

Parameters:

rgen - RandomGenerator used to set the state of this RandomGenerator.

toString

public String toString()

String representation of this RandomGenerator.

Overrides:

toString in class Object

Returns:

String representation of this RandomGenerator.