From 0432dd066e312d73c840ab8e8445dfeb8fbdbf4d Mon Sep 17 00:00:00 2001
From: Thorsten Sommer <mail@tsommer.org>
Date: Sat, 26 Sep 2020 12:00:46 +0200
Subject: [PATCH] Added NextNumber for (0, 1)

---
 FastRng/Double/Distributions/Gamma.cs | 8 ++++----
 FastRng/Double/IRandom.cs             | 4 +++-
 FastRng/Double/MultiThreadedRng.cs    | 6 ++++--
 3 files changed, 11 insertions(+), 7 deletions(-)

diff --git a/FastRng/Double/Distributions/Gamma.cs b/FastRng/Double/Distributions/Gamma.cs
index 266c381..dc9f90a 100644
--- a/FastRng/Double/Distributions/Gamma.cs
+++ b/FastRng/Double/Distributions/Gamma.cs
@@ -6,6 +6,8 @@ namespace FastRng.Double.Distributions
 {
     public sealed class Gamma : IDistribution
     {
+        private static readonly IDistribution NORMAL_DISTRIBUTION = new Normal();
+        
         private double shape = 1.0;
         
         public IRandom Random { get; set; }
@@ -35,7 +37,6 @@ namespace FastRng.Double.Distributions
             
             if (shape >= 1.0)
             {
-                var distNormal = new Normal();
                 var d = shape - 1.0 / 3.0;
                 var c = 1.0 / Math.Sqrt(9.0 * d);
                 while(true)
@@ -43,7 +44,7 @@ namespace FastRng.Double.Distributions
                     double x, v;
                     do
                     {
-                        x = await this.Random.NextNumber(0, 1, distNormal, token);
+                        x = await this.Random.NextNumber(NORMAL_DISTRIBUTION, token);
                         v = 1.0 + c * x;
                     }
                     while (v <= 0.0);
@@ -59,8 +60,7 @@ namespace FastRng.Double.Distributions
             else
             {
                 var dist = new Gamma{ Scale = 1, Shape = 1 + this.Shape};
-                
-                var g = await this.Random.NextNumber(0.0f, 1.0f, dist, token); // TODO: Use double
+                var g = await this.Random.NextNumber(dist, token);
                 var w = await this.Random.GetUniform(token);
                 return this.Scale * g * Math.Pow(w, 1.0 / this.Shape);
             }
diff --git a/FastRng/Double/IRandom.cs b/FastRng/Double/IRandom.cs
index 54f1511..396d0b8 100644
--- a/FastRng/Double/IRandom.cs
+++ b/FastRng/Double/IRandom.cs
@@ -12,7 +12,9 @@ namespace FastRng.Double
         
         public ValueTask<ulong> NextNumber(ulong rangeStart, ulong rangeEnd, IDistribution distribution, CancellationToken cancel = default);
         
-        public ValueTask<float> NextNumber(float rangeStart, float rangeEnd, IDistribution distribution, CancellationToken cancel = default);
+        public ValueTask<double> NextNumber(double rangeStart, double rangeEnd, IDistribution distribution, CancellationToken cancel = default);
+        
+        public ValueTask<double> NextNumber(IDistribution distribution, CancellationToken cancel = default);
 
         public void StopProducer();
     }
diff --git a/FastRng/Double/MultiThreadedRng.cs b/FastRng/Double/MultiThreadedRng.cs
index 3518eef..50e75b7 100644
--- a/FastRng/Double/MultiThreadedRng.cs
+++ b/FastRng/Double/MultiThreadedRng.cs
@@ -167,7 +167,7 @@ namespace FastRng.Double
             return (ulong) ((distributedValue * range) + rangeStart);
         }
 
-        public async ValueTask<float> NextNumber(float rangeStart, float rangeEnd, IDistribution distribution, CancellationToken cancel = default(CancellationToken))
+        public async ValueTask<double> NextNumber(double rangeStart, double rangeEnd, IDistribution distribution, CancellationToken cancel = default(CancellationToken))
         {
             if (rangeStart > rangeEnd)
             {
@@ -180,9 +180,11 @@ namespace FastRng.Double
             distribution.Random = this;
 
             var distributedValue = await distribution.GetDistributedValue(cancel);
-            return (float) ((distributedValue * range) + rangeStart);
+            return (distributedValue * range) + rangeStart;
         }
 
+        public async ValueTask<double> NextNumber(IDistribution distribution, CancellationToken cancel = default) => await this.NextNumber(0.0, 1.0, distribution, cancel);
+
         public void StopProducer() => this.producerToken.Cancel();
 
         #endregion