Package it.unimi.dsi.util

Class XorShift64StarRandomGenerator

java.lang.Object
org.apache.commons.math3.random.AbstractRandomGenerator
it.unimi.dsi.util.XorShift64StarRandomGenerator
All Implemented Interfaces:
RandomGenerator
@Deprecated public class XorShift64StarRandomGenerator extends AbstractRandomGenerator
Deprecated.
Use SplitMix64RandomGenerator instead.
A fast, good-quality pseudorandom number generator that combines George Marsaglia's Xorshift generators (described in “Xorshift RNGs”, Journal of Statistical Software, 8:1−6, 2003) with a multiplication.

  • Constructor Details

    • XorShift64StarRandomGenerator

      public XorShift64StarRandomGenerator()
      Deprecated.
      Creates a new generator seeded using Util.randomSeed().

    • XorShift64StarRandomGenerator

      public XorShift64StarRandomGenerator(long seed)
      Deprecated.
      Creates a new generator using a given seed.
      Parameters:
      seed - a nonzero seed for the generator (if zero, the generator will be seeded with Long.MIN_VALUE).

  • Method Details

    • nextLong

      public long nextLong()
      Deprecated.
      Specified by:
      nextLong in interface RandomGenerator
      Overrides:
      nextLong in class AbstractRandomGenerator

    • nextInt

      public int nextInt()
      Deprecated.
      Specified by:
      nextInt in interface RandomGenerator
      Overrides:
      nextInt in class AbstractRandomGenerator

    • nextInt

      public int nextInt(int n)
      Deprecated.
      Returns a pseudorandom, approximately uniformly distributed int value between 0 (inclusive) and the specified value (exclusive), drawn from this random number generator's sequence.

      The hedge “approximately” is due to the fact that to be always faster than ThreadLocalRandom we return the upper 63 bits of nextLong() modulo n instead of using Random's fancy algorithm (which nextLong(long) uses though). This choice introduces a bias: the numbers from 0 to 263 mod n are slightly more likely than the other ones. In the worst case, “more likely” means 1.00000000023 times more likely, which is in practice undetectable. If for some reason you need truly uniform generation, just use nextLong(long).

      Specified by:
      nextInt in interface RandomGenerator
      Overrides:
      nextInt in class AbstractRandomGenerator
      Parameters:
      n - the positive bound on the random number to be returned.
      Returns:
      the next pseudorandom int value between 0 (inclusive) and n (exclusive).

    • nextLong

      public long nextLong(long n)
      Deprecated.
      Returns a pseudorandom uniformly distributed long value between 0 (inclusive) and the specified value (exclusive), drawn from this random number generator's sequence. The algorithm used to generate the value guarantees that the result is uniform, provided that the sequence of 64-bit values produced by this generator is.
      Parameters:
      n - the positive bound on the random number to be returned.
      Returns:
      the next pseudorandom long value between 0 (inclusive) and n (exclusive).

    • nextDouble

      public double nextDouble()
      Deprecated.
      Specified by:
      nextDouble in interface RandomGenerator
      Specified by:
      nextDouble in class AbstractRandomGenerator

    • nextFloat

      public float nextFloat()
      Deprecated.
      Specified by:
      nextFloat in interface RandomGenerator
      Overrides:
      nextFloat in class AbstractRandomGenerator

    • nextBoolean

      public boolean nextBoolean()
      Deprecated.
      Specified by:
      nextBoolean in interface RandomGenerator
      Overrides:
      nextBoolean in class AbstractRandomGenerator

    • nextBytes

      public void nextBytes(byte[] bytes)
      Deprecated.
      Specified by:
      nextBytes in interface RandomGenerator
      Overrides:
      nextBytes in class AbstractRandomGenerator

    • setSeed

      public void setSeed(long seed)
      Deprecated.
      Sets the seed of this generator.

      The seed will be passed through HashCommon.murmurHash3(long). In this way, if the user passes a small value we will avoid the short irregular transient associated with states with a very small number of bits set.

      Specified by:
      setSeed in interface RandomGenerator
      Specified by:
      setSeed in class AbstractRandomGenerator
      Parameters:
      seed - a nonzero seed for this generator (if zero, the generator will be seeded with Long.MIN_VALUE).

    • setState

      public void setState(long state)
      Deprecated.
      Sets the state of this generator.
      Parameters:
      state - the new state for this generator (must be nonzero).