From 39959e8a2e92aa8b0b0933a06cd7247c658fa45e Mon Sep 17 00:00:00 2001
From: Lucas Godshalk <lucasmg91@gmail.com>
Date: Sat, 29 Apr 2017 07:33:23 -0400
Subject: [PATCH] Handle empty statistics (#482)

This prevents most of the fields from being set to NaN.
---
 src/Numerics/Statistics/RunningStatistics.cs | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/src/Numerics/Statistics/RunningStatistics.cs b/src/Numerics/Statistics/RunningStatistics.cs
index b5aa7f67..72f3c839 100644
--- a/src/Numerics/Statistics/RunningStatistics.cs
+++ b/src/Numerics/Statistics/RunningStatistics.cs
@@ -237,6 +237,15 @@ namespace MathNet.Numerics.Statistics
         /// </summary>
         public static RunningStatistics Combine(RunningStatistics a, RunningStatistics b)
         {
+            if (a._n == 0)
+            {
+                return b;
+            }
+            else if (b._n == 0)
+            {
+                return a;
+            }
+            
             long n = a._n + b._n;
             double d = b._m1 - a._m1;
             double d2 = d*d;