Generate: more tests, fix PeriodicMapSequence

src/Numerics/Generate.cs

@@ -348,7 +348,7 @@ namespace MathNet.Numerics
                 {
                     x %= amplitude;
                     phase = x;
-                    k = 0;
+                    k = 1;
                 }
 
                 yield return map(x);

src/UnitTests/GenerateTests.cs

@@ -148,6 +148,18 @@ namespace MathNet.Numerics.UnitTests
             Assert.That(Generate.Periodic(8, 2.0, 0.25, Constants.Pi2).Select(Math.Sin), Is.EqualTo(new[] { 0.0, isq2, 1.0, isq2, 0.0, -isq2, -1.0, -isq2 }).Within(1e-12).AsCollection);
         }
 
+        [Test]
+        public void PeriodicConsistentWithSinusoidal()
+        {
+            Assert.That(
+                Generate.PeriodicMap(100, Math.Sin, 16.0, 2.0, Constants.Pi2),
+                Is.EqualTo(Generate.Sinusoidal(100, 16.0, 2.0, 1.0)).Within(1e-12).AsCollection);
+
+            Assert.That(
+                Generate.PeriodicMapSequence(Math.Sin, 16.0, 2.0, Constants.Pi2).Take(100).ToArray(),
+                Is.EqualTo(Generate.SinusoidalSequence(16.0, 2.0, 1.0).Take(100).ToArray()).Within(1e-12).AsCollection);
+        }
+
         [Test]
         public void PreiodicConsistentWithSequence()
         {