Unit Tests: Interpolation IV

src/UnitTests/InterpolationTests/BulirschStoerRationalTest.cs

@@ -0,0 +1,78 @@
+// <copyright file="BulirschStoerRationalTest.cs" company="Math.NET">
+// Math.NET Numerics, part of the Math.NET Project
+// http://numerics.mathdotnet.com
+// http://github.com/mathnet/mathnet-numerics
+// http://mathnetnumerics.codeplex.com
+//
+// Copyright (c) 2002-2011 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.InterpolationTests
+{
+    using Interpolation;
+    using Interpolation.Algorithms;
+    using NUnit.Framework;
+
+    [TestFixture]
+    public class BulirschStoerRationalTest
+    {
+        readonly double[] _t = new[] { 0d, 1, 3, 4, 5 };
+        readonly double[] _x = new[] { 0d, 3, 1000, -1000, 3 };
+
+        /// <summary>
+        /// Verifies that the interpolation matches the given value at all the provided sample points.
+        /// </summary>
+        [Test]
+        public void FitsAtSamplePoints()
+        {
+            IInterpolation interpolation = new BulirschStoerRationalInterpolation(_t, _x);
+
+            for (int i = 0; i < _x.Length; i++)
+            {
+                Assert.AreEqual(_x[i], interpolation.Interpolate(_t[i]), "A Exact Point " + i);
+            }
+        }
+
+        /// <summary>
+        /// Verifies that at points other than the provided sample points, the interpolation matches the one computed by Maple as a reference.
+        /// </summary>
+        /// <remarks>
+        /// Maple:
+        /// with(CurveFitting);
+        /// evalf(subs({x=0.1},RationalInterpolation([[0,0],[1,3],[3,1000],[4,-1000], [5,3]], x)),20);
+        /// </remarks>
+        [Test, Sequential]
+        public void FitsAtArbitraryPointsWithMaple(
+            [Values(0.1, 0.4, 1.1, 3.01, 3.02, 3.03, 3.1, 3.2, 4.5, 10.0, -10.0)] double t,
+            [Values(.19389203383553566255, .88132900698869875369, 3.5057665681580626913, 1548.7666642693586902, 3362.2564334253633516, -22332.603641443806014, -440.30323769822443789, -202.42421196280566349, 21.208249625210155439, -4.8936986959784751517, -3.6017584308603731307)] double x,
+            [Values(1e-14, 1e-14, 1e-15, 1e-10, 1e-10, 1e-8, 1e-11, 1e-12, 1e-12, 1e-13, 1e-13)] double maxAbsoluteError)
+        {
+            IInterpolation interpolation = new BulirschStoerRationalInterpolation(_t, _x);
+
+            Assert.AreEqual(x, interpolation.Interpolate(t), maxAbsoluteError, "Interpolation at {0}", t);
+        }
+
+        // NOTE: No test for the linear case because this algorithms is incredibly bad at this.
+    }
+}

src/UnitTests/UnitTests.csproj

@@ -113,6 +113,7 @@
     <Compile Include="IntegralTransformsTests\MatchingNaiveTransformTest.cs" />
     <Compile Include="IntegralTransformsTests\ParsevalTheoremTest.cs" />
     <Compile Include="IntegrationTests\IntegrationTest.cs" />
+    <Compile Include="InterpolationTests\BulirschStoerRationalTest.cs" />
     <Compile Include="InterpolationTests\FloaterHormannRationalTest.cs" />
     <Compile Include="InterpolationTests\EquidistantPolynomialTest.cs" />
     <Compile Include="InterpolationTests\NevillePolynomialTest.cs" />