Api Suggestion for combinatorics/counting

Signed-off-by: Marcus Cuda <marcus@cuda.net>

src/Managed.UnitTests/CombinatoricsTests/CombinatoricsCountingTest.cs

@@ -0,0 +1,88 @@
+// <copyright file="CombinatoricsCountingTest.cs" company="Math.NET">
+// Math.NET Numerics, part of the Math.NET Project
+// http://mathnet.opensourcedotnet.info
+//
+// Copyright (c) 2009 Math.NET
+//
+// Permission is hereby granted, free of charge, to any person
+// obtaining a copy of this software and associated documentation
+// files (the "Software"), to deal in the Software without
+// restriction, including without limitation the rights to use,
+// copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the
+// Software is furnished to do so, subject to the following
+// conditions:
+//
+// The above copyright notice and this permission notice shall be
+// included in all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+// EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
+// OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+// NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
+// HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
+// WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+// FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+// OTHER DEALINGS IN THE SOFTWARE.
+// </copyright>
+
+namespace MathNet.Numerics.UnitTests.CombinatoricsTests
+{
+    using MbUnit.Framework;
+
+    [TestFixture]
+    public class CombinatoricsCountingTest
+    {
+        [Test, Ignore("Depending on Special Functions")]
+        [Row(0, 0, 1)]
+        [Row(1, 0, 1)]
+        [Row(10, 0, 1)]
+        [Row(10, 2, 90)]
+        [Row(10, 4, 5040)]
+        [Row(10, 6, 151200)]
+        [Row(10, 9, 3628800)]
+        [Row(10, 10, 3628800)]
+        public void CanCountVariations(int n, int k, long expected)
+        {
+            Assert.AreEqual(expected, Combinatorics.Variations(n, k), "Count the number of variations without repetition");
+        }
+
+        [Test]
+        [Row(0, 1)]
+        [Row(10, 11)]
+        [Row(0, -1)]
+        [Row(1, -1)]
+        [Row(-1, 0)]
+        [Row(-1, 1)]
+        public void OutOfRangeVariationsMustCountToZero(int n, int k)
+        {
+            Assert.AreEqual(0, Combinatorics.Variations(n, k), "The number of variations without repetition but out of the range must be 0.");
+        }
+
+        [Test]
+        [Row(0, 0, 1)]
+        [Row(1, 0, 1)]
+        [Row(10, 0, 1)]
+        [Row(10, 2, 100)]
+        [Row(10, 4, 10000)]
+        [Row(10, 6, 1000000)]
+        [Row(10, 9, 1000000000)]
+        [Row(10, 10, 10000000000)]
+        [Row(10, 11, 100000000000)]
+        public void CanCountVariationsWithRepetition(int n, int k, long expected)
+        {
+            Assert.AreEqual(expected, Combinatorics.VariationsWithRepetition(n, k), "Count the number of variations with repetition");
+        }
+
+        [Test]
+        [Row(0, 1)]
+        [Row(0, -1)]
+        [Row(1, -1)]
+        [Row(-1, 0)]
+        [Row(-1, 1)]
+        public void OutOfRangeVariationsWithRepetitionMustCountToZero(int n, int k)
+        {
+            Assert.AreEqual(0, Combinatorics.VariationsWithRepetition(n, k), "The number of variations with repetition but out of the range must be 0.");
+        }
+    }
+}

src/Managed.UnitTests/Managed.UnitTests.csproj

@@ -57,6 +57,7 @@
     <Reference Include="System.Xml" />
   </ItemGroup>
   <ItemGroup>
+    <Compile Include="CombinatoricsTests\CombinatoricsCountingTest.cs" />
     <Compile Include="ComplexTest.cs" />
     <Compile Include="Properties\AssemblyInfo.cs" />
   </ItemGroup>

src/Managed/Combinatorics.cs

@@ -0,0 +1,70 @@
+// <copyright file="Combinatorics.cs" company="Math.NET">
+// Math.NET Numerics, part of the Math.NET Project
+// http://mathnet.opensourcedotnet.info
+//
+// Copyright (c) 2009 Math.NET
+//
+// Permission is hereby granted, free of charge, to any person
+// obtaining a copy of this software and associated documentation
+// files (the "Software"), to deal in the Software without
+// restriction, including without limitation the rights to use,
+// copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the
+// Software is furnished to do so, subject to the following
+// conditions:
+//
+// The above copyright notice and this permission notice shall be
+// included in all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+// EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
+// OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+// NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
+// HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
+// WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+// FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+// OTHER DEALINGS IN THE SOFTWARE.
+// </copyright>
+
+namespace MathNet.Numerics
+{
+    using System;
+
+    /// <summary>
+    /// Enumerative Combinatorics and Counting.
+    /// </summary>
+    public static class Combinatorics
+    {
+        /// <summary>
+        /// Computes the number of variations without repetition. The order matters and each object can be chosen only once.
+        /// </summary>
+        /// <param name="n">Number of elements in the set.</param>
+        /// <param name="k">Number of elements to choose from the set. Each element is chosen at most once.</param>
+        /// <returns>Maximum number of distinct variations.</returns>
+        public static double Variations(int n, int k)
+        {
+            if(k < 0 || n < 0 || k > n)
+            {
+                return 0;
+            }
+
+            throw new NotImplementedException();
+        }
+
+        /// <summary>
+        /// Computes the number of variations with repetition. The order matters and each object can be chosen more than once.
+        /// </summary>
+        /// <param name="n">Number of elements in the set.</param>
+        /// <param name="k">Number of elements to choose from the set. Each element is chosen 0, 1 or multiple times.</param>
+        /// <returns>Maximum number of distinct variations with repetition.</returns>
+        public static double VariationsWithRepetition(int n, int k)
+        {
+            if(k < 0 || n < 0)
+            {
+                return 0;
+            }
+
+            return Math.Pow(n, k);
+        }
+    }
+}

src/Managed/Managed.csproj

@@ -38,6 +38,7 @@
     <Reference Include="System.Xml" />
   </ItemGroup>
   <ItemGroup>
+    <Compile Include="Combinatorics.cs" />
     <Compile Include="Complex.cs" />
     <Compile Include="Properties\AssemblyInfo.cs" />
     <Compile Include="Properties\Resources.Designer.cs">