Merge pull request #2712 from MediaBrowser/dev

Dev

1 files changed, 51 insertions, 0 deletions

diff --git a/Emby.Common.Implementations/TextEncoding/NLangDetect/Extensions/RandomExtensions.cs b/Emby.Common.Implementations/TextEncoding/NLangDetect/Extensions/RandomExtensions.cs
new file mode 100644
index 000000000..d55ca80df
--- /dev/null
+++ b/Emby.Common.Implementations/TextEncoding/NLangDetect/Extensions/RandomExtensions.cs
@@ -0,0 +1,51 @@
+using System;
+
+namespace NLangDetect.Core.Extensions
+{
+  public static class RandomExtensions
+  {
+    private const double _Epsilon = 2.22044604925031E-15;
+
+    private static readonly object _mutex = new object();
+
+    private static double _nextNextGaussian;
+    private static bool _hasNextNextGaussian;
+
+    /// <summary>
+    /// Returns the next pseudorandom, Gaussian ("normally") distributed double value with mean 0.0 and standard deviation 1.0 from this random number generator's sequence.
+    /// The general contract of nextGaussian is that one double value, chosen from (approximately) the usual normal distribution with mean 0.0 and standard deviation 1.0, is pseudorandomly generated and returned.
+    /// </summary>
+    /// <remarks>
+    /// Taken from: http://download.oracle.com/javase/6/docs/api/java/util/Random.html (nextGaussian())
+    /// </remarks>
+    public static double NextGaussian(this Random random)
+    {
+      lock (_mutex)
+      {
+        if (_hasNextNextGaussian)
+        {
+          _hasNextNextGaussian = false;
+
+          return _nextNextGaussian;
+        }
+
+        double v1, v2, s;
+
+        do
+        {
+          v1 = 2.0 * random.NextDouble() - 1.0; // between -1.0 and 1.0
+          v2 = 2.0 * random.NextDouble() - 1.0; // between -1.0 and 1.0
+          s = v1 * v1 + v2 * v2;
+        }
+        while (s >= 1.0 || Math.Abs(s - 0.0) < _Epsilon);
+
+        double multiplier = Math.Sqrt(-2.0 * Math.Log(s) / s);
+
+        _nextNextGaussian = v2 * multiplier;
+        _hasNextNextGaussian = true;
+
+        return v1 * multiplier;
+      }
+    }
+  }
+}