Package it.unich.jgmp

Class RandState

  • public class RandState
extends java.lang.Object
    Current state of a random number generator. This class enapsulates the native gmp_randstate_t data type, see the Random Number Function page of the GMP manual. In determining the names and signatures of the methods of the RandState class, we adopted the following rules:
    • the function gmp_randclear is only used internally;
    • the obsolete function gmp_randinit is not exposed by the RandState class;
    • if the function name begins with gmp_randinit, we create a static method caleed baseName which returns a new RandState object;
    • otherwise, we create a method baseName which calls the original function, implicitly using this as the first non-constant gmp_randstate_t parameter.
    Other methods and constructors which conform to standard Java naming conventions might be provided.

    In general, all the parameters which are not provided implicitly to the original GMP function through this should be provided explicitly.

    Note that it is not safe for two threads to generate a random number from the same RandState simultaneously, since this involves an update of the object.

    • Nested Class Summary

      Nested Classes 
      Modifier and Type Class Description
      private static class  RandState.RandomStateCleaner
      Cleaning action for the RandState class.

    • Field Summary

      Fields 
      Modifier and Type Field Description
      private GmpRandstateT randstateNative
      The pointer to the native gmp_randstate_t object.

    • Constructor Summary

      Constructors 
      Modifier Constructor Description
        RandState()
      Builds the default random state.
      private RandState​(GmpRandstateT pointer)
      A private constructor which build a RandState starting from a pointer to its native data object.
        RandState​(RandState state)
      Builds a copy of the specified random state.

    • Field Detail

      • randstateNative

        private GmpRandstateT randstateNative
        The pointer to the native gmp_randstate_t object.

    • Constructor Detail

      • RandState

        private RandState​(GmpRandstateT pointer)
        A private constructor which build a RandState starting from a pointer to its native data object. The native object needs to be already initialized.

      • RandState

        public RandState()
        Builds the default random state.

      • RandState

        public RandState​(RandState state)
        Builds a copy of the specified random state.

    • Method Detail

      • getNative

        public GmpRandstateT getNative()
        Returns the native pointer to the GMP object.

      • randinitDefault

        public static RandState randinitDefault()
        Returns the default random state.

      • randinitMt

        public static RandState randinitMt()
        Returns a random state for a Mersenne Twister algorithm. This algorithm is fast and has good randomness properties.

      • randinitLc2Exp

        public static RandState randinitLc2Exp​(MPZ a,
                                       long c,
                                       long m2exp)
        Returns a random state for a linear congruential algorithm. See the GMP function gmp_randinit_lc_2exp.

      • randinitLc2ExpSize

        public static RandState randinitLc2ExpSize​(long size)
        Returns a random state for a linear congruential algorithm. See the GMP function gmp_randinit_lc_2exp_size.
        Throws:
        java.lang.IllegalArgumentException - if size is too big.

      • randinitSet

        public RandState randinitSet​(RandState op)
        Returns a random state which is a copy of op.

      • randseed

        public RandState randseed​(MPZ seed)
        Sets an initial seed value into this.

      • randseedUi

        public RandState randseedUi​(long seed)
        Sets an initial seed value into this.

      • urandombUi

        public long urandombUi​(long n)
        Returns a uniformly distributed random number of n bits, in the range 0 to (2n-1) inclusive. n must be less than or equal to the number of bits in a native unsigned long.

      • urandommUi

        public long urandommUi​(long n)
        Returns a uniformly distributed random number in the range 0 to (n - 1) inclusive.