Distributions: fix Geometric distribution sampling

src/Numerics/Distributions/Geometric.cs

@@ -241,7 +241,7 @@ namespace MathNet.Numerics.Distributions
         /// <returns>One sample from the distribution implied by <paramref name="p"/>.</returns>
         static int SampleUnchecked(System.Random rnd, double p)
         {
-            return p == 1.0 ? 1 : (int) Math.Ceiling(-Math.Log(1.0 - rnd.NextDouble(), 1.0 - p));
+            return p == 1.0 ? 1 : (int)Math.Ceiling(Math.Log(1.0 - rnd.NextDouble(), 1.0 - p));
         }
 
         /// <summary>

src/UnitTests/DistributionTests/CommonDistributionTests.cs

@@ -59,7 +59,7 @@ namespace MathNet.Numerics.UnitTests.DistributionTests
                 new Categorical(new[] { 0.7, 0.3 }),
                 //new ConwayMaxwellPoisson(0.2, 0.4),
                 new DiscreteUniform(1, 10),
-                //new Geometric(0.2),
+                new Geometric(0.2),
                 new Hypergeometric(20, 3, 5),
                 //new NegativeBinomial(4, 0.6),
                 //new Poisson(0.4),