AbstractRandomGenerator (Commons MATH 2.2)

java.lang.Object
- org.apache.commons.math.random.AbstractRandomGenerator

All Implemented Interfaces:

RandomGenerator
```
public abstract class AbstractRandomGenerator
extends java.lang.Object
implements RandomGenerator
```
Abstract class implementing the RandomGenerator interface. Default implementations for all methods other than nextDouble() and setSeed(long) are provided.
All data generation methods are based on code nextDouble(). Concrete implementations must override this method and should provide better / more performant implementations of the other methods if the underlying PRNG supplies them.

Since:

1.1

Version:

$Revision: 990655 $ $Date: 2010-08-29 23:49:40 +0200 (dim. 29 août 2010) $

Field Summary

Fields
Modifier and Type Field and Description

private double cachedNormalDeviate
Cached random normal value.

Fields
Modifier and Type	Field and Description
`private double`	`cachedNormalDeviate` Cached random normal value.

Constructor Summary

Constructors
Constructor and Description

AbstractRandomGenerator()
Construct a RandomGenerator.

Constructors
Constructor and Description
`AbstractRandomGenerator()` Construct a RandomGenerator.

Method Summary

All Methods Instance Methods Abstract Methods Concrete Methods
Modifier and Type	Method and Description
`void`	`clear()` Clears the cache used by the default implementation of `nextGaussian()`.
`boolean`	`nextBoolean()` Returns the next pseudorandom, uniformly distributed `boolean` value from this random number generator's sequence.
`void`	`nextBytes(byte[] bytes)` Generates random bytes and places them into a user-supplied byte array.
`abstract double`	`nextDouble()` Returns the next pseudorandom, uniformly distributed `double` value between `0.0` and `1.0` from this random number generator's sequence.
`float`	`nextFloat()` Returns the next pseudorandom, uniformly distributed `float` value between `0.0` and `1.0` from this random number generator's sequence.
`double`	`nextGaussian()` Returns the next pseudorandom, Gaussian ("normally") distributed `double` value with mean `0.0` and standard deviation `1.0` from this random number generator's sequence.
`int`	`nextInt()` Returns the next pseudorandom, uniformly distributed `int` value from this random number generator's sequence.
`int`	`nextInt(int n)` Returns a pseudorandom, uniformly distributed `int` value between 0 (inclusive) and the specified value (exclusive), drawn from this random number generator's sequence.
`long`	`nextLong()` Returns the next pseudorandom, uniformly distributed `long` value from this random number generator's sequence.
`void`	`setSeed(int seed)` Sets the seed of the underlying random number generator using an `int` seed.
`void`	`setSeed(int[] seed)` Sets the seed of the underlying random number generator using an `int` array seed.
`abstract void`	`setSeed(long seed)` Sets the seed of the underyling random number generator using a `long` seed.

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Field Detail
  - cachedNormalDeviate
```
private double cachedNormalDeviate
```
    Cached random normal value. The default implementation for nextGaussian() generates pairs of values and this field caches the second value so that the full algorithm is not executed for every activation. The value Double.NaN signals that there is no cached value. Use clear() to clear the cached value.
- Constructor Detail
  - AbstractRandomGenerator
```
public AbstractRandomGenerator()
```
    Construct a RandomGenerator.
- Method Detail
  - clear
```
public void clear()
```
    Clears the cache used by the default implementation of nextGaussian(). Implemementations that do not override the default implementation of nextGaussian should call this method in the implementation of setSeed(long)
  - setSeed
```
public void setSeed(int seed)
```
    Sets the seed of the underlying random number generator using an int seed.
    Sequences of values generated starting with the same seeds should be identical.
    
    Specified by:
    
    setSeed in interface RandomGenerator
    
    Parameters:
    
    seed - the seed value
  - setSeed
```
public void setSeed(int[] seed)
```
    Sets the seed of the underlying random number generator using an int array seed.
    Sequences of values generated starting with the same seeds should be identical.
    
    Specified by:
    
    setSeed in interface RandomGenerator
    
    Parameters:
    
    seed - the seed value
  - setSeed
```
public abstract void setSeed(long seed)
```
    Sets the seed of the underyling random number generator using a long seed. Sequences of values generated starting with the same seeds should be identical.
    Implementations that do not override the default implementation of nextGaussian should include a call to clear() in the implementation of this method.
    
    Specified by:
    
    setSeed in interface RandomGenerator
    
    Parameters:
    
    seed - the seed value
  - nextBytes
```
public void nextBytes(byte[] bytes)
```
    Generates random bytes and places them into a user-supplied byte array. The number of random bytes produced is equal to the length of the byte array.
    The default implementation fills the array with bytes extracted from random integers generated using nextInt().
    
    Specified by:
    
    nextBytes in interface RandomGenerator
    
    Parameters:
    
    bytes - the non-null byte array in which to put the random bytes
  - nextInt
```
public int nextInt()
```
    Returns the next pseudorandom, uniformly distributed int value from this random number generator's sequence. All 2³² possible int values should be produced with (approximately) equal probability.
    The default implementation provided here returns
```
 (int) (nextDouble() * Integer.MAX_VALUE)
 
```
    Specified by:
    
    nextInt in interface RandomGenerator
    
    Returns:
    
    the next pseudorandom, uniformly distributed int value from this random number generator's sequence
  - nextInt
```
public int nextInt(int n)
```
    Returns a pseudorandom, uniformly distributed int value between 0 (inclusive) and the specified value (exclusive), drawn from this random number generator's sequence.
    The default implementation returns
```
 (int) (nextDouble() * n
 
```
    Specified by:
    
    nextInt in interface RandomGenerator
    
    Parameters:
    
    n - the bound on the random number to be returned. Must be positive.
    
    Returns:
    
    a pseudorandom, uniformly distributed int value between 0 (inclusive) and n (exclusive).
    
    Throws:
    
    NotStrictlyPositiveException - if n <= 0.
  - nextLong
```
public long nextLong()
```
    Returns the next pseudorandom, uniformly distributed long value from this random number generator's sequence. All 2⁶⁴ possible long values should be produced with (approximately) equal probability.
    The default implementation returns
```
 (long) (nextDouble() * Long.MAX_VALUE)
 
```
    Specified by:
    
    nextLong in interface RandomGenerator
    
    Returns:
    
    the next pseudorandom, uniformly distributed long value from this random number generator's sequence
  - nextBoolean
```
public boolean nextBoolean()
```
    Returns the next pseudorandom, uniformly distributed boolean value from this random number generator's sequence.
    The default implementation returns
```
 nextDouble() <= 0.5
 
```
    Specified by:
    
    nextBoolean in interface RandomGenerator
    
    Returns:
    
    the next pseudorandom, uniformly distributed boolean value from this random number generator's sequence
  - nextFloat
```
public float nextFloat()
```
    Returns the next pseudorandom, uniformly distributed float value between 0.0 and 1.0 from this random number generator's sequence.
    The default implementation returns
```
 (float) nextDouble() 
 
```
    Specified by:
    
    nextFloat in interface RandomGenerator
    
    Returns:
    
    the next pseudorandom, uniformly distributed float value between 0.0 and 1.0 from this random number generator's sequence
  - nextDouble
```
public abstract double nextDouble()
```
    Returns the next pseudorandom, uniformly distributed double value between 0.0 and 1.0 from this random number generator's sequence.
    This method provides the underlying source of random data used by the other methods.
    
    Specified by:
    
    nextDouble in interface RandomGenerator
    
    Returns:
    
    the next pseudorandom, uniformly distributed double value between 0.0 and 1.0 from this random number generator's sequence
  - nextGaussian
```
public double nextGaussian()
```
    Returns the next pseudorandom, Gaussian ("normally") distributed double value with mean 0.0 and standard deviation 1.0 from this random number generator's sequence.
    The default implementation uses the Polar Method due to G.E.P. Box, M.E. Muller and G. Marsaglia, as described in D. Knuth, The Art of Computer Programming, 3.4.1C.
    
    The algorithm generates a pair of independent random values. One of these is cached for reuse, so the full algorithm is not executed on each activation. Implementations that do not override this method should make sure to call clear() to clear the cached value in the implementation of setSeed(long).
    
    Specified by:
    
    nextGaussian in interface RandomGenerator
    
    Returns:
    
    the next pseudorandom, Gaussian ("normally") distributed double value with mean 0.0 and standard deviation 1.0 from this random number generator's sequence

Class AbstractRandomGenerator

Field Summary

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Field Detail

cachedNormalDeviate

Constructor Detail

AbstractRandomGenerator

Method Detail

clear

setSeed

setSeed

setSeed

nextBytes

nextInt

nextInt

nextLong

nextBoolean

nextFloat

nextDouble

nextGaussian