Initial

FastRngTests/Double/Distributions/Exponential.cs

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+using System;
+using System.Diagnostics.CodeAnalysis;
+using System.Linq;
+using System.Threading.Tasks;
+using FastRng.Double;
+using NUnit.Framework;
+
+namespace FastRngTests.Double.Distributions
+{
+    [ExcludeFromCodeCoverage]
+    public class Exponential
+    {
+        [Test]
+        [Category(TestCategories.COVER)]
+        [Category(TestCategories.NORMAL)]
+        public async Task TestExponentialDistribution01()
+        {
+            const double MEAN = 1.5;
+            const double VARIANCE = MEAN * MEAN;
+            
+            var dist = new FastRng.Double.Distributions.Exponential{ Mean = MEAN };
+            var stats = new RunningStatistics();
+            var rng = new MultiThreadedRng();
+            
+            for (var n = 0; n < 100_000; n++)
+                stats.Push(await rng.NextNumber(dist));
+            
+            rng.StopProducer();
+            TestContext.WriteLine($"mean={MEAN} vs. {stats.Mean}");
+            TestContext.WriteLine($"variance={VARIANCE} vs {stats.Variance}");
+            
+            Assert.That(stats.Mean, Is.EqualTo(MEAN).Within(0.4), "Mean is out of range");
+            Assert.That(stats.Variance, Is.EqualTo(VARIANCE).Within(0.4), "Variance is out of range");
+        }
+        
+        [Test]
+        [Category(TestCategories.COVER)]
+        [Category(TestCategories.NORMAL)]
+        public async Task TestExponentialGeneratorWithRange01()
+        {
+            var rng = new MultiThreadedRng();
+            var samples = new double[1_000];
+            for (var n = 0; n < samples.Length; n++)
+                samples[n] = await rng.NextNumber(-1.0, 1.0, new FastRng.Double.Distributions.Exponential());
+            
+            rng.StopProducer();
+            Assert.That(samples.Min(), Is.GreaterThanOrEqualTo(-1.0), "Min out of range");
+            Assert.That(samples.Max(), Is.LessThanOrEqualTo(1.0), "Max out of range");
+        }
+        
+        [Test]
+        [Category(TestCategories.COVER)]
+        [Category(TestCategories.NORMAL)]
+        public async Task TestExponentialGeneratorWithRange02()
+        {
+            var rng = new MultiThreadedRng();
+            var samples = new double[1_000];
+            for (var n = 0; n < samples.Length; n++)
+                samples[n] = await rng.NextNumber(0.0, 1.0, new FastRng.Double.Distributions.Exponential());
+            
+            rng.StopProducer();
+            Assert.That(samples.Min(), Is.GreaterThanOrEqualTo(0.0), "Min is out of range");
+            Assert.That(samples.Max(), Is.LessThanOrEqualTo(1.0), "Max is out of range");
+        }
+
+        [Test]
+        [Category(TestCategories.COVER)]
+        [Category(TestCategories.NORMAL)]
+        public void ParameterTest01()
+        {
+            var dist = new FastRng.Double.Distributions.Exponential();
+            
+            Assert.Throws<ArgumentOutOfRangeException>(() => dist.Mean = 0);
+            Assert.Throws<ArgumentOutOfRangeException>(() => dist.Mean = -78);
+            Assert.DoesNotThrow(() => dist.Mean = 0.0001);
+            Assert.DoesNotThrow(() => dist.Mean = 4);
+        }
+
+        [Test]
+        [Category(TestCategories.COVER)]
+        [Category(TestCategories.NORMAL)]
+        public async Task NoRandomNumberGenerator01()
+        {
+            var dist = new FastRng.Double.Distributions.Exponential();
+            Assert.DoesNotThrowAsync(async () => await dist.GetDistributedValue());
+            Assert.That(await dist.GetDistributedValue(), Is.NaN);
+        }
+    }
+}