QuadraticSplineTest.cs

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// Math.NET Numerics, part of the Math.NET Project
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using MathNet.Numerics.Interpolation;
using MathNet.Numerics.Random;
using NUnit.Framework;

namespace MathNet.Numerics.Tests.InterpolationTests
{
    [TestFixture, Category("Interpolation")]
    public class QuadraticSplineTest
    {
        readonly double[] _x = { -20.0, -10.0, -5.0, 0, 5.0, 10.0, 20.0 };
        readonly double[] _c0 = { -3.0, -2.0, 1.0, 0.0, 1.0, 2.0 };
        readonly double[] _c1 = { -2.0, -1.0, 0.0, 1.0, 2.0, 3.0 };
        readonly double[] _c2 = { -1.0, 0.0, 1.0, 2.0, 3.0, 4.0 };

        /// <summary>
        /// Verifies that the 3rd derivative matches the given value at all the provided sample points.
        /// </summary>
        [Test]
        public void ThirdDerivative()
        {
            var rnd = new SystemRandomSource(10);
            IInterpolation it = new QuadraticSpline(_x, _c0, _c1, _c2);

            Assert.AreEqual(0, it.Differentiate3(rnd.NextDouble()));
        }
    }
}