GammaUpper tests

src/Runtime/Core/Maths/SpecialFunctions.cs

@@ -1337,11 +1337,12 @@ namespace Microsoft.ML.Probabilistic.Math
                 throw new ArgumentException($"x ({x}) < 0");
             if (!regularized)
             {
-                if (a < 1 && x >= 0.1) return GammaUpperConFrac2(a, x, regularized);
+                if (a < 1 && x >= 1) return GammaUpperConFrac2(a, x, regularized);
                 else if (a <= GammaSmallX)
                 {
                     if (x < 1)
                     {
+                        // This case is needed by TruncatedGamma_GetMeanPower_WithinBounds
                         double logx = Math.Log(x);
                         return GammaUpperSeries1(a, x, logx, regularized) + GammaUpperConFrac2(a, 1, regularized);
                     }
@@ -1622,7 +1623,7 @@ namespace Microsoft.ML.Probabilistic.Math
                 double term;
                 if (a + i == 0)
                 {
-                    term = -Math.Log(x);
+                    term = -logx;
                 }
                 else
                 {

test/TestApp/Program.cs

@@ -84,6 +84,8 @@ namespace TestApp
             Stopwatch watch = new Stopwatch();
             watch.Start();
 
+            new OperatorTests().GammaUpper_IsDecreasingInX();
+
             bool runAllTests = false;
             if (runAllTests)
             {

test/Tests/Distributions/DistributionTests.cs

@@ -124,7 +124,7 @@ namespace Microsoft.ML.Probabilistic.Tests
             long count = 0;
             Parallel.ForEach(new[] {
                 GammaPower.FromShapeAndRate(1.7976931348623157E+308, 1.7976931348623157E+308, -1.7976931348623157E+308),
-            }.Concat(OperatorTests.GammaPowers(1000000)), gammaPower =>
+            }.Concat(OperatorTests.GammaPowers(100000)), gammaPower =>
             {
                 double argmax = double.NaN;
                 double max = double.NegativeInfinity;

test/Tests/Operators/OperatorTests.cs

@@ -374,14 +374,22 @@ namespace Microsoft.ML.Probabilistic.Tests
                 double x2 = 1.7976931348623466;
                 x2 = 0.10000000000000024;
                 x2 = 0.099999999999923289;
+                x2 = 1 - 1e-15;
                 double fp = double.NaN;
                 bool anyIncreasing = false;
-                for (int i = 0; i < 10000; i++)
+                Stopwatch watch = new Stopwatch();
+                for (int i = 0; i < 100; i++)
                 {
                     double f = MMath.GammaUpper(4.94065645841247E-324, x2, false);
+                    watch.Restart();
+                    for (int j = 0; j < 10000; j++)
+                    {
+                        f = MMath.GammaUpper(4.94065645841247E-324, x2, false);
+                    }
+                    var elapsed = watch.ElapsedMilliseconds;
                     string star = (f > fp) ? "increasing" : "";
                     anyIncreasing |= (f > fp);
-                    Trace.WriteLine($"{x2:g17} {f:g17} {star}");
+                    Trace.WriteLine($"{x2:g17} {f:g17} {elapsed} {star}");
                     x2 = MMath.NextDouble(x2);
                     fp = f;
                 }