Exponential extends AbstractContinousDistribution { @Override public double pdf(double x) { if (x < 0.0) { return 0.0; } return lambda * Math.exp(-x * 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 testPdf() { checkPdf(new Exponential(13.0, null), 13.0); }