Package io.github.olyutorskii.aletojio.rng.fibo

Class LagFib

java.lang.Object

io.github.olyutorskii.aletojio.rng.fibo.LagFib

All Implemented Interfaces:

RndInt32

public class LagFib
extends Object
implements RndInt32

Lagged Fibonacci Pseudo Random Generator(LFG).

Recurrence relation sequences : X(n) = X(n-j) + X(n-k)

If generation(1,2) given, it generates the so-called Fibonacchi numbers sequence.

Typical generation pairs.

• (1,2)
• (7,10)
• (24,55)
• (353,521)
• (861,1279)
• (9739,23209)

Seed values are mixed well if the number of generations(k,j) are prime to each other.

If polynomial: y = x**k + x**j + 1 is primitive over GF(2), generator has more long period.

See Also:

• Lagged_Fibonacci_generator (Wikipedia)

Constructor Summary

Constructors

Constructor	Description
LagFib(int genYounger, int genOlder)	Constructor.

Method Summary

Modifier and Type	Method	Description
protected int	binOp(int tap1, int tap2)	Binary operation between 2 taps.
protected void	checkSeeds(int... initVec)	Check seeds.
static boolean	hasOdd(int... iVec)	Check whether int array contains odd number or not.
int	nextInt32()	Return next random number as 32bit int with random sign-bit.
void	setSeed(int... initVec)	Set seed.

Methods inherited from class java.lang.Object

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

Constructor Details

LagFib

public LagFib(int genYounger,
 int genOlder)
       throws IndexOutOfBoundsException,
IllegalArgumentException

Constructor.

Number of generation must be greater than 0.

Older generation number must be greater than younger.

Parameters:

genYounger - younger past generation X(n-j)

genOlder - older past generation X(n-k)

Throws:

IndexOutOfBoundsException - Given generation is out of range

IllegalArgumentException - older generation is not greater than youger generation

Method Details

hasOdd

public static boolean hasOdd(int... iVec)
                      throws NullPointerException

Check whether int array contains odd number or not.

Parameters:

iVec - int array

Returns:

true if odd number exists.

Throws:

NullPointerException - argument is null

checkSeeds

protected void checkSeeds(int... initVec)
                   throws IllegalArgumentException

Check seeds.

Parameters:

initVec - seeds

Throws:

IllegalArgumentException - illegal seeds

setSeed

public void setSeed(int... initVec)
             throws NullPointerException,
IndexOutOfBoundsException,
IllegalArgumentException

Set seed.

At least one of the seeds must be odd number.

Seeds must be old-generation length array.

Parameters:

initVec - seed array

Throws:

NullPointerException - argument is null

IndexOutOfBoundsException - unmatch seeds length

IllegalArgumentException - odd number is not be found

binOp

protected int binOp(int tap1,
 int tap2)

Binary operation between 2 taps.

Just adding.

Parameters:

tap1 - tap 1st

tap2 - tap 2nd

Returns:

result

nextInt32

public int nextInt32()

Return next random number as 32bit int with random sign-bit.

Specified by:

nextInt32 in interface RndInt32

Returns:

random number