Accord.Tests.Math.GammaTest.DigammaTest C# (CSharp) Method

        public void DigammaTest()
        {
            double[] x = { 1, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0 };

            double[] expected =    
            {
                -0.5772156649015329,
                -0.4237549404110768, 
                -0.2890398965921883,  
                -0.1691908888667997,
                -0.06138454458511615,
                 0.03648997397857652,
                 0.1260474527734763,
                 0.208547874873494,
                 0.2849914332938615,
                 0.3561841611640597,
                 0.4227843350984671,
            };

            for (int i = 0; i < x.Length; i++)
            {
                double xi = x[i];
                double expectedi = expected[i];
                double actual = Gamma.Digamma(xi);

                Assert.AreEqual(expectedi, actual, 1e-10);
            }
        }