MRG31k3p
umontreal.iro.lecuyer.rng

Class MRG31k3p

  • All Implemented Interfaces:
    Serializable, Cloneable, CloneableRandomStream, RandomStream


    public class MRG31k3pextends RandomStreamBase
    Extends the abstract class RandomStreamBase, thus implementing the RandomStream interface indirectly. The backbone generator is the combined multiple recursive generator (CMRG) MRG31k3p proposed by L'Ecuyer and Touzin, implemented in 32-bit integer arithmetic. This RNG has a period length of approximately 2185. The values of V, W and Z are 262, 272 and 2134 respectively. (See RandomStream for their definition.) The seed and the state of a stream at any given step are six-dimensional vectors of 32-bit integers. The default initial seed is (12345, 12345, 12345, 12345, 12345, 12345). The method nextValue provides 31 bits of precision.

    The difference between the RNG of class MRG32k3a and this one is that this one has all its coefficients of the form a = ±2q±2r. This permits a faster implementation than for arbitrary coefficients. On a 32-bit computer, MRG31k3p is about twice as fast as MRG32k3a. On the other hand, the latter does a little better in the spectral test and has been more extensively tested.

    See Also:
    Serialized Form
    • Constructor Detail

      • MRG31k3p

        public MRG31k3p()
        Constructs a new stream, initialized at its beginning. Its seed is Z = 2134 steps away from the previous seed.
      • MRG31k3p

        public MRG31k3p(String name)
        Constructs a new stream with the identifier name (used when formatting the stream state).
        Parameters:
        name - name of the stream
    • Method Detail

      • setPackageSeed

        public static void setPackageSeed(int[] seed)
        Sets the initial seed for the class MRG31k3p to the six integers of the vector seed[0..5]. This will be the initial state (or seed) of the next created stream. By default, if this method is not called, the first stream is created with the seed (12345, 12345, 12345, 12345, 12345, 12345). If it is called, the first 3 values of the seed must all be less than m1 = 2147483647, and not all 0; and the last 3 values must all be less than m2 = 2147462579, and not all 0.
        Parameters:
        seed - array of 6 elements representing the seed
      • setSeed

        public void setSeed(int[] seed)
        Use of this method is strongly discouraged. Initializes the stream at the beginning of a stream with the initial seed seed[0..5]. This vector must satisfy the same conditions as in setPackageSeed. This method only affects the specified stream, all the others are not modified, so the beginning of the streams are no longer spaced Z values apart. For this reason, this method should be used only in very exceptional situations; proper use of reset... and of the stream constructor is preferable.
        Parameters:
        seed - array of 6 integers representing the new seed
      • getState

        public int[] getState()
        Returns the current state Cg of this stream. This is a vector of 6 integers represented. This method is convenient if we want to save the state for subsequent use.
        Returns:
        the current state of the generator

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