public void ValidateDensityLn(double lower, double upper)
        {
            var n = new ContinuousUniform(lower, upper);

            for (var i = 0; i < 11; i++)
            {
                var x = i - 5.0;
                if (x >= lower && x <= upper)
                {
                    Assert.AreEqual(-Math.Log(upper - lower), n.DensityLn(x));
                    Assert.AreEqual(-Math.Log(upper - lower), ContinuousUniform.PDFLn(lower, upper, x));
                }
                else
                {
                    Assert.AreEqual(double.NegativeInfinity, n.DensityLn(x));
                    Assert.AreEqual(double.NegativeInfinity, ContinuousUniform.PDFLn(lower, upper, x));
                }
            }
        }