SpecialFunctions: increase iteration limit of BetaRegularized from 100 to 120

src/Numerics/SpecialFunctions/Beta.cs

@@ -121,7 +121,7 @@ namespace MathNet.Numerics
             var symmetryTransformation = x >= (a + 1.0) / (a + b + 2.0);
 
             /* Continued fraction representation */
-            const int maxIterations = 100;
+            const int maxIterations = 120;
             var eps = Precision.DoublePrecision;
             var fpmin = 0.0.Increment() / eps;
 

src/UnitTests/SpecialFunctionsTests/SpecialFunctionsTests.cs

@@ -267,6 +267,14 @@ namespace MathNet.Numerics.UnitTests.SpecialFunctionsTests
             AssertHelpers.AlmostEqualRelative(f, SpecialFunctions.BetaRegularized(a, b, x), 11);
         }
 
+        [Test]
+        public void BetaRegularizedLargeArguments()
+        {
+            Assert.That(
+                SpecialFunctions.BetaRegularized(3846.2382301675848, 738420369.64263761, 0.0000052331266889206809),
+                Is.EqualTo(0.61624368331298802128).Within(1e-5));
+        }
+
         /// <summary>
         /// Logit function.
         /// </summary>