From e0e7292324604478142c2596507b45967e65244a Mon Sep 17 00:00:00 2001
From: bbieniek <baltazar@bieniek.org.pl>
Date: Tue, 17 Feb 2015 15:58:20 +0100
Subject: [PATCH] When DF parameter was high, the CDF returned NaN value. This
 was resolved by using the GammaLowerRegularized function straight from the
 CDF instead of division and multipliciation by Gamma function.

---
 src/Numerics/Distributions/ChiSquared.cs | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/Numerics/Distributions/ChiSquared.cs b/src/Numerics/Distributions/ChiSquared.cs
index 53a2a7ba..4076a090 100644
--- a/src/Numerics/Distributions/ChiSquared.cs
+++ b/src/Numerics/Distributions/ChiSquared.cs
@@ -356,7 +356,7 @@ namespace MathNet.Numerics.Distributions
                 throw new ArgumentException(Resources.InvalidDistributionParameters);
             }
 
-            return SpecialFunctions.GammaLowerIncomplete(freedom/2.0, x/2.0)/SpecialFunctions.Gamma(freedom/2.0);
+            return SpecialFunctions.GammaLowerRegularized(freedom/2.0, x/2.0);
         }
 
         /// <summary>