mathnet-numerics/src/UnitTests/LinearAlgebraTests/Single/Solvers/IteratorTest.cs

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using System;
using System.Collections.Generic;
using MathNet.Numerics.LinearAlgebra.Single;
using MathNet.Numerics.LinearAlgebra.Single.Solvers;
using MathNet.Numerics.LinearAlgebra.Solvers;
using NUnit.Framework;

namespace MathNet.Numerics.UnitTests.LinearAlgebraTests.Single.Solvers
{
    /// <summary>
    /// Iterator tests
    /// </summary>
    [TestFixture]
    public class IteratorTest
    {
        /// <summary>
        /// Determine status without stop criteria throws <c>ArgumentException</c>.
        /// </summary>
        [Test]
        public void DetermineStatusWithoutStopCriteriaDoesNotThrow()
        {
            var iterator = new Iterator<float>();
            Assert.DoesNotThrow(() => iterator.DetermineStatus(
                0,
                DenseVector.Create(3, i => 4),
                DenseVector.Create(3, i => 5),
                DenseVector.Create(3, i => 6)));
        }

        /// <summary>
        /// Determine status with negative iteration number throws <c>ArgumentOutOfRangeException</c>.
        /// </summary>
        [Test]
        public void DetermineStatusWithNegativeIterationNumberThrowsArgumentOutOfRangeException()
        {
            var criteria = new List<IIterationStopCriterium<float>>
            {
                new FailureStopCriterium(),
                new DivergenceStopCriterium(),
                new IterationCountStopCriterium<float>(),
                new ResidualStopCriterium<float>(1e-6)
            };
            var iterator = new Iterator<float>(criteria);

            Assert.Throws<ArgumentOutOfRangeException>(() => iterator.DetermineStatus(
                -1,
                DenseVector.Create(3, i => 4),
                DenseVector.Create(3, i => 5),
                DenseVector.Create(3, i => 6)));
        }

        /// <summary>
        /// Can determine status.
        /// </summary>
        [Test]
        public void DetermineStatus()
        {
            var criteria = new List<IIterationStopCriterium<float>>
            {
                new FailureStopCriterium(),
                new DivergenceStopCriterium(),
                new IterationCountStopCriterium<float>(1)
            };

            var iterator = new Iterator<float>(criteria);

            // First step, nothing should happen.
            iterator.DetermineStatus(
                0,
                DenseVector.Create(3, i => 4),
                DenseVector.Create(3, i => 4),
                DenseVector.Create(3, i => 4));
            Assert.AreEqual(IterationStatus.Continue, iterator.Status, "Incorrect status");

            // Second step, should run out of iterations.
            iterator.DetermineStatus(
                1,
                DenseVector.Create(3, i => 4),
                DenseVector.Create(3, i => 4),
                DenseVector.Create(3, i => 4));
            Assert.AreEqual(IterationStatus.StoppedWithoutConvergence, iterator.Status, "Incorrect status");
        }

        /// <summary>
        /// Can reset to precalculation state.
        /// </summary>
        [Test]
        public void ResetToPrecalculationState()
        {
            var criteria = new List<IIterationStopCriterium<float>>
            {
                new FailureStopCriterium(),
                new DivergenceStopCriterium(),
                new IterationCountStopCriterium<float>(1)
            };

            var iterator = new Iterator<float>(criteria);

            // First step, nothing should happen.
            iterator.DetermineStatus(
                0,
                DenseVector.Create(3, i => 4),
                DenseVector.Create(3, i => 4),
                DenseVector.Create(3, i => 4));
            Assert.AreEqual(IterationStatus.Continue, iterator.Status, "Incorrect status");

            iterator.Reset();
            Assert.AreEqual(IterationStatus.Continue, iterator.Status, "Incorrect status");
            Assert.AreEqual(IterationStatus.Continue, criteria[0].Status, "Incorrect status");
            Assert.AreEqual(IterationStatus.Continue, criteria[1].Status, "Incorrect status");
            Assert.AreEqual(IterationStatus.Continue, criteria[2].Status, "Incorrect status");
        }
    }
}