Package org.apache.commons.math3.random
Class ISAACRandom
- java.lang.Object
-
- org.apache.commons.math3.random.BitsStreamGenerator
-
- org.apache.commons.math3.random.ISAACRandom
-
- All Implemented Interfaces:
java.io.Serializable
,RandomGenerator
public class ISAACRandom extends BitsStreamGenerator implements java.io.Serializable
ISAAC: a fast cryptographic pseudo-random number generator
ISAAC (Indirection, Shift, Accumulate, Add, and Count) generates 32-bit random numbers. ISAAC has been designed to be cryptographically secure and is inspired by RC4. Cycles are guaranteed to be at least 240 values long, and they are 28295 values long on average. The results are uniformly distributed, unbiased, and unpredictable unless you know the seed.
This code is based (with minor changes and improvements) on the original implementation of the algorithm by Bob Jenkins.- Since:
- 3.0
- See Also:
- Serialized Form
-
-
Field Summary
Fields Modifier and Type Field Description private int[]
arr
Service variable.private int
count
Count through the results in rsl[]private static int
GLD_RATIO
The golden ratioprivate static int
H_SIZE
Half-size of rsl[] and mem[]private int
isaacA
Accumulatorprivate int
isaacB
The last resultprivate int
isaacC
Counter, guarantees cycle is at least 2^40private int
isaacI
Service variable.private int
isaacJ
Service variable.private int
isaacX
Service variable.private static int
MASK
For pseudo-random lookupprivate int[]
mem
The internal stateprivate int[]
rsl
The results given to the userprivate static long
serialVersionUID
Serializable version identifierprivate static int
SIZE
Size of rsl[] and mem[]private static int
SIZE_L
Log of size of rsl[] and mem[]
-
Constructor Summary
Constructors Constructor Description ISAACRandom()
Creates a new ISAAC random number generator.ISAACRandom(int[] seed)
Creates a new ISAAC random number generator using an int array seed.ISAACRandom(long seed)
Creates a new ISAAC random number generator using a single long seed.
-
Method Summary
All Methods Instance Methods Concrete Methods Modifier and Type Method Description private void
initState()
Initialize, or reinitialize, this instance of rand.private void
isaac()
Generate 256 resultsprivate void
isaac2()
Intermediate internal loop.private void
isaac3()
Lowest level internal loop.protected int
next(int bits)
Generate next pseudorandom number.void
setSeed(int seed)
Sets the seed of the underlying random number generator using anint
seed.void
setSeed(int[] seed)
Sets the seed of the underlying random number generator using anint
array seed.void
setSeed(long seed)
Sets the seed of the underlying random number generator using along
seed.private void
setState(int start)
Set the state by copying the internal arrays.private void
shuffle()
Shuffle array.-
Methods inherited from class org.apache.commons.math3.random.BitsStreamGenerator
clear, nextBoolean, nextBytes, nextBytes, nextDouble, nextFloat, nextGaussian, nextInt, nextInt, nextLong, nextLong
-
-
-
-
Field Detail
-
serialVersionUID
private static final long serialVersionUID
Serializable version identifier- See Also:
- Constant Field Values
-
SIZE_L
private static final int SIZE_L
Log of size of rsl[] and mem[]- See Also:
- Constant Field Values
-
SIZE
private static final int SIZE
Size of rsl[] and mem[]- See Also:
- Constant Field Values
-
H_SIZE
private static final int H_SIZE
Half-size of rsl[] and mem[]- See Also:
- Constant Field Values
-
MASK
private static final int MASK
For pseudo-random lookup- See Also:
- Constant Field Values
-
GLD_RATIO
private static final int GLD_RATIO
The golden ratio- See Also:
- Constant Field Values
-
rsl
private final int[] rsl
The results given to the user
-
mem
private final int[] mem
The internal state
-
count
private int count
Count through the results in rsl[]
-
isaacA
private int isaacA
Accumulator
-
isaacB
private int isaacB
The last result
-
isaacC
private int isaacC
Counter, guarantees cycle is at least 2^40
-
arr
private final int[] arr
Service variable.
-
isaacX
private int isaacX
Service variable.
-
isaacI
private int isaacI
Service variable.
-
isaacJ
private int isaacJ
Service variable.
-
-
Constructor Detail
-
ISAACRandom
public ISAACRandom()
Creates a new ISAAC random number generator.
The instance is initialized using a combination of the current time and system hash code of the instance as the seed.
-
ISAACRandom
public ISAACRandom(long seed)
Creates a new ISAAC random number generator using a single long seed.- Parameters:
seed
- Initial seed.
-
ISAACRandom
public ISAACRandom(int[] seed)
Creates a new ISAAC random number generator using an int array seed.- Parameters:
seed
- Initial seed. Ifnull
, the seed will be related to the current time.
-
-
Method Detail
-
setSeed
public void setSeed(int seed)
Sets the seed of the underlying random number generator using anint
seed.Sequences of values generated starting with the same seeds should be identical.
- Specified by:
setSeed
in interfaceRandomGenerator
- Specified by:
setSeed
in classBitsStreamGenerator
- Parameters:
seed
- the seed value
-
setSeed
public void setSeed(long seed)
Sets the seed of the underlying random number generator using along
seed.Sequences of values generated starting with the same seeds should be identical.
- Specified by:
setSeed
in interfaceRandomGenerator
- Specified by:
setSeed
in classBitsStreamGenerator
- Parameters:
seed
- the seed value
-
setSeed
public void setSeed(int[] seed)
Sets the seed of the underlying random number generator using anint
array seed.Sequences of values generated starting with the same seeds should be identical.
- Specified by:
setSeed
in interfaceRandomGenerator
- Specified by:
setSeed
in classBitsStreamGenerator
- Parameters:
seed
- the seed value
-
next
protected int next(int bits)
Generate next pseudorandom number.This method is the core generation algorithm. It is used by all the public generation methods for the various primitive types
BitsStreamGenerator.nextBoolean()
,BitsStreamGenerator.nextBytes(byte[])
,BitsStreamGenerator.nextDouble()
,BitsStreamGenerator.nextFloat()
,BitsStreamGenerator.nextGaussian()
,BitsStreamGenerator.nextInt()
,BitsStreamGenerator.next(int)
andBitsStreamGenerator.nextLong()
.- Specified by:
next
in classBitsStreamGenerator
- Parameters:
bits
- number of random bits to produce- Returns:
- random bits generated
-
isaac
private void isaac()
Generate 256 results
-
isaac2
private void isaac2()
Intermediate internal loop.
-
isaac3
private void isaac3()
Lowest level internal loop.
-
initState
private void initState()
Initialize, or reinitialize, this instance of rand.
-
shuffle
private void shuffle()
Shuffle array.
-
setState
private void setState(int start)
Set the state by copying the internal arrays.- Parameters:
start
- First index intomem
array.
-
-