Exponential extends AbstractContinousDistribution { @Override public double nextDouble() { return -Math.log1p(-randomDouble()) / lambda; } Exponential(double lambda, Random randomGenerator); @Override double cdf(double x); @Override double nextDouble(); @Override double pdf(double x); void setState(double lambda); @Override String toString();  }
@Test public void testNextDouble() throws Exception { double[] x = { -0.01, 0.1053605, 0.2231436, 0.3566749, 0.5108256, 0.6931472, 0.9162907, 1.2039728, 1.6094379, 2.3025851 }; Exponential dist = new Exponential(1, RandomUtils.getRandom()); for (double lambda : new double[]{13.0, 0.02, 1.6}) { dist.setState(lambda); checkEmpiricalDistribution(dist, 10000, lambda); DistributionChecks.checkDistribution(dist, x, 0, 1 / lambda, 10000); } }