/**
* Returns the RandomGenerator used to generate non-secure random data.
*
* <p>Creates and initializes a default generator if null.
*
* @return the Random used to generate random data
* @since 1.1
*/
private RandomGenerator getRan() {
if (rand == null) {
rand = new JDKRandomGenerator();
rand.setSeed(System.currentTimeMillis());
}
return rand;
}
/**
* Returns the SecureRandom used to generate secure random data.
*
* <p>Creates and initializes if null. Uses {@code System.currentTimeMillis() +
* System.identityHashCode(this)} as the default seed.
*
* @return the SecureRandom used to generate secure random data, wrapped in a {@link
* RandomGenerator}.
*/
private RandomGenerator getSecRan() {
if (secRand == null) {
secRand = RandomGeneratorFactory.createRandomGenerator(new SecureRandom());
secRand.setSeed(System.currentTimeMillis() + System.identityHashCode(this));
}
return secRand;
}
@Test
public void testNextInversionDeviate() {
// Set the seed for the default random generator
RandomGenerator rg = new Well19937c(100);
RandomDataGenerator rdg = new RandomDataGenerator(rg);
double[] quantiles = new double[10];
for (int i = 0; i < 10; i++) {
quantiles[i] = rdg.nextUniform(0, 1);
}
// Reseed again so the inversion generator gets the same sequence
rg.setSeed(100);
BetaDistribution betaDistribution =
new BetaDistribution(rg, 2, 4, BetaDistribution.DEFAULT_INVERSE_ABSOLUTE_ACCURACY);
/*
* Generate a sequence of deviates using inversion - the distribution function
* evaluated at the random value from the distribution should match the uniform
* random value used to generate it, which is stored in the quantiles[] array.
*/
for (int i = 0; i < 10; i++) {
double value = betaDistribution.sample();
Assert.assertEquals(betaDistribution.cumulativeProbability(value), quantiles[i], 10E-9);
}
}
/** Reseeds the random number generator with the current time in milliseconds. */
public void reSeed() {
if (rand == null) {
rand = new JDKRandomGenerator();
}
rand.setSeed(System.currentTimeMillis());
}
/**
* Reseeds the random number generator with the supplied seed.
*
* <p>Will create and initialize if null.
*
* @param seed the seed value to use
*/
public void reSeed(long seed) {
if (rand == null) {
rand = new JDKRandomGenerator();
}
rand.setSeed(seed);
}
