ExponentialDistribution extends AbstractRealDistribution { public double cumulativeProbability(double x) { double ret; if (x <= 0.0) { ret = 0.0; } else { ret = 1.0 - FastMath.exp(-x / mean); } return ret; } ExponentialDistribution(double mean);  ExponentialDistribution(double mean, double inverseCumAccuracy);  ExponentialDistribution(RandomGenerator rng, double mean);  ExponentialDistribution(RandomGenerator rng,
                                   double mean,
                                   double inverseCumAccuracy); double getMean(); double density(double x); @Override double logDensity(double x); double cumulativeProbability(double x); @Override double inverseCumulativeProbability(double p); @Override double sample(); double getNumericalMean(); double getNumericalVariance(); double getSupportLowerBound(); double getSupportUpperBound(); boolean isSupportLowerBoundInclusive(); boolean isSupportUpperBoundInclusive(); boolean isSupportConnected(); static final double DEFAULT_INVERSE_ABSOLUTE_ACCURACY; }
@Test public void testCumulativeProbability2() { double actual = getDistribution().cumulativeProbability(0.25, 0.75); Assert.assertEquals(0.0905214, actual, 10e-4); }