imagingbook.pub.noise.hashing

Class HashFun

java.lang.Object

imagingbook.pub.noise.hashing.HashFun

Direct Known Subclasses:

Hash32, HashPermute

public abstract class HashFun
extends Object

This class is the abstract superclass of various hash functions. It cannot be instantiated directly, but its subclasses can. Two static methods create() and create(seed) are provided for convenience. Typical use:

   HashFun hf = new HashFun.create(); // or, alternatively,
   HashFun hf = new Hash32Ward(seed);
   double g = hf.hash(u); // g is in [-1,+1]
   double g = hf.hash(u,v);
   double[] g = hf.hash(u,v,w); 

Omit seed in the constructor call to get a random seed hash function of the specified type.

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	HashFun()
protected	HashFun(int seed)

Method Summary

Modifier and Type	Method and Description
static HashFun	create()
static HashFun	create(int seed) Creates a new HashFun object initialized with seed.
abstract double	hash(int u)
abstract double[]	hash(int[] p)
abstract double[]	hash(int u, int v)
abstract double[]	hash(int u, int v, int w)
protected int	makeRandomSeed()

Methods inherited from class java.lang.Object

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

Constructor Detail

HashFun

protected HashFun()

HashFun

protected HashFun(int seed)

Method Detail

create

public static HashFun create()

Returns:

A new HashFun object. Has32Shift is used as the default type.

create

public static HashFun create(int seed)

Creates a new HashFun object initialized with seed. Has32Shift is used as the default type.

Parameters:

seed - the seed

Returns:

a new HashFun object

makeRandomSeed

protected int makeRandomSeed()

hash

public abstract double hash(int u)

hash

public abstract double[] hash(int u,
                              int v)

hash

public abstract double[] hash(int u,
                              int v,
                              int w)

hash

public abstract double[] hash(int[] p)