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package org.apache.commons.math3.random;


This class implements the WELL19937c pseudo-random number generator from François Panneton, Pierre L'Ecuyer and Makoto Matsumoto.

This generator is described in a paper by François Panneton, Pierre L'Ecuyer and Makoto Matsumoto Improved Long-Period Generators Based on Linear Recurrences Modulo 2 ACM Transactions on Mathematical Software, 32, 1 (2006). The errata for the paper are in wellrng-errata.txt.

See Also:
Since:2.2
/** This class implements the WELL19937c pseudo-random number generator * from Fran&ccedil;ois Panneton, Pierre L'Ecuyer and Makoto Matsumoto. * <p>This generator is described in a paper by Fran&ccedil;ois Panneton, * Pierre L'Ecuyer and Makoto Matsumoto <a * href="http://www.iro.umontreal.ca/~lecuyer/myftp/papers/wellrng.pdf">Improved * Long-Period Generators Based on Linear Recurrences Modulo 2</a> ACM * Transactions on Mathematical Software, 32, 1 (2006). The errata for the paper * are in <a href="http://www.iro.umontreal.ca/~lecuyer/myftp/papers/wellrng-errata.txt">wellrng-errata.txt</a>.</p> * @see <a href="http://www.iro.umontreal.ca/~panneton/WELLRNG.html">WELL Random number generator</a> * @since 2.2 */
public class Well19937c extends AbstractWell {
Serializable version identifier.
/** Serializable version identifier. */
private static final long serialVersionUID = -7203498180754925124L;
Number of bits in the pool.
/** Number of bits in the pool. */
private static final int K = 19937;
First parameter of the algorithm.
/** First parameter of the algorithm. */
private static final int M1 = 70;
Second parameter of the algorithm.
/** Second parameter of the algorithm. */
private static final int M2 = 179;
Third parameter of the algorithm.
/** Third parameter of the algorithm. */
private static final int M3 = 449;
Creates a new random number generator.

The instance is initialized using the current time as the seed.

/** Creates a new random number generator. * <p>The instance is initialized using the current time as the * seed.</p> */
public Well19937c() { super(K, M1, M2, M3); }
Creates a new random number generator using a single int seed.
Params:
  • seed – the initial seed (32 bits integer)
/** Creates a new random number generator using a single int seed. * @param seed the initial seed (32 bits integer) */
public Well19937c(int seed) { super(K, M1, M2, M3, seed); }
Creates a new random number generator using an int array seed.
Params:
  • seed – the initial seed (32 bits integers array), if null the seed of the generator will be related to the current time
/** Creates a new random number generator using an int array seed. * @param seed the initial seed (32 bits integers array), if null * the seed of the generator will be related to the current time */
public Well19937c(int[] seed) { super(K, M1, M2, M3, seed); }
Creates a new random number generator using a single long seed.
Params:
  • seed – the initial seed (64 bits integer)
/** Creates a new random number generator using a single long seed. * @param seed the initial seed (64 bits integer) */
public Well19937c(long seed) { super(K, M1, M2, M3, seed); }
{@inheritDoc}
/** {@inheritDoc} */
@Override protected int next(final int bits) { final int indexRm1 = iRm1[index]; final int indexRm2 = iRm2[index]; final int v0 = v[index]; final int vM1 = v[i1[index]]; final int vM2 = v[i2[index]]; final int vM3 = v[i3[index]]; final int z0 = (0x80000000 & v[indexRm1]) ^ (0x7FFFFFFF & v[indexRm2]); final int z1 = (v0 ^ (v0 << 25)) ^ (vM1 ^ (vM1 >>> 27)); final int z2 = (vM2 >>> 9) ^ (vM3 ^ (vM3 >>> 1)); final int z3 = z1 ^ z2; int z4 = z0 ^ (z1 ^ (z1 << 9)) ^ (z2 ^ (z2 << 21)) ^ (z3 ^ (z3 >>> 21)); v[index] = z3; v[indexRm1] = z4; v[indexRm2] &= 0x80000000; index = indexRm1; // add Matsumoto-Kurita tempering // to get a maximally-equidistributed generator z4 ^= (z4 << 7) & 0xe46e1700; z4 ^= (z4 << 15) & 0x9b868000; return z4 >>> (32 - bits); } }