// <copyright file="IterationCountStopCriterion.cs" company="Math.NET">
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// Math.NET Numerics, part of the Math.NET Project
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// http://numerics.mathdotnet.com
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// http://github.com/mathnet/mathnet-numerics
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//
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// Copyright (c) 2009-2014 Math.NET
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//
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// Permission is hereby granted, free of charge, to any person
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// obtaining a copy of this software and associated documentation
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// files (the "Software"), to deal in the Software without
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// restriction, including without limitation the rights to use,
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// copy, modify, merge, publish, distribute, sublicense, and/or sell
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// copies of the Software, and to permit persons to whom the
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// Software is furnished to do so, subject to the following
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// conditions:
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//
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// The above copyright notice and this permission notice shall be
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// included in all copies or substantial portions of the Software.
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//
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// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
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// EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
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// OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
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// NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
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// OTHER DEALINGS IN THE SOFTWARE.
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// </copyright>
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using System;
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using System.Diagnostics;
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namespace IStation.Numerics.LinearAlgebra.Solvers
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{
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/// <summary>
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/// Defines an <see cref="IIterationStopCriterion{T}"/> that monitors the numbers of iteration
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/// steps as stop criterion.
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/// </summary>
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public sealed class IterationCountStopCriterion<T> : IIterationStopCriterion<T> where T : struct, IEquatable<T>, IFormattable
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{
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/// <summary>
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/// The default value for the maximum number of iterations the process is allowed
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/// to perform.
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/// </summary>
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public const int DefaultMaximumNumberOfIterations = 1000;
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/// <summary>
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/// The maximum number of iterations the calculation is allowed to perform.
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/// </summary>
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int _maximumNumberOfIterations;
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/// <summary>
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/// The status of the calculation
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/// </summary>
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IterationStatus _status = IterationStatus.Continue;
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/// <summary>
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/// Initializes a new instance of the <see cref="IterationCountStopCriterion{T}"/> class with the default maximum
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/// number of iterations.
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/// </summary>
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public IterationCountStopCriterion() : this(DefaultMaximumNumberOfIterations)
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{
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}
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/// <summary>
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/// Initializes a new instance of the <see cref="IterationCountStopCriterion{T}"/> class with the specified maximum
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/// number of iterations.
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/// </summary>
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/// <param name="maximumNumberOfIterations">The maximum number of iterations the calculation is allowed to perform.</param>
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public IterationCountStopCriterion(int maximumNumberOfIterations)
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{
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if (maximumNumberOfIterations < 1)
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{
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throw new ArgumentOutOfRangeException(nameof(maximumNumberOfIterations));
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}
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_maximumNumberOfIterations = maximumNumberOfIterations;
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}
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/// <summary>
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/// Gets or sets the maximum number of iterations the calculation is allowed to perform.
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/// </summary>
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/// <exception cref="ArgumentOutOfRangeException">Thrown if the <c>Maximum</c> is set to a negative value.</exception>
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public int MaximumNumberOfIterations
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{
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[DebuggerStepThrough]
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get => _maximumNumberOfIterations;
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[DebuggerStepThrough]
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set
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{
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if (value < 1)
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{
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throw new ArgumentOutOfRangeException(nameof(value));
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}
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_maximumNumberOfIterations = value;
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}
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}
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/// <summary>
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/// Returns the maximum number of iterations to the default.
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/// </summary>
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public void ResetMaximumNumberOfIterationsToDefault()
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{
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_maximumNumberOfIterations = DefaultMaximumNumberOfIterations;
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}
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/// <summary>
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/// Determines the status of the iterative calculation based on the stop criteria stored
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/// by the current <see cref="IterationCountStopCriterion{T}"/>. Result is set into <c>Status</c> field.
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/// </summary>
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/// <param name="iterationNumber">The number of iterations that have passed so far.</param>
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/// <param name="solutionVector">The vector containing the current solution values.</param>
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/// <param name="sourceVector">The right hand side vector.</param>
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/// <param name="residualVector">The vector containing the current residual vectors.</param>
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/// <remarks>
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/// The individual stop criteria may internally track the progress of the calculation based
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/// on the invocation of this method. Therefore this method should only be called if the
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/// calculation has moved forwards at least one step.
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/// </remarks>
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public IterationStatus DetermineStatus(int iterationNumber, Vector<T> solutionVector, Vector<T> sourceVector, Vector<T> residualVector)
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{
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if (iterationNumber < 0)
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{
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throw new ArgumentOutOfRangeException(nameof(iterationNumber));
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}
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_status = iterationNumber >= _maximumNumberOfIterations ? IterationStatus.StoppedWithoutConvergence : IterationStatus.Continue;
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return _status;
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}
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/// <summary>
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/// Gets the current calculation status.
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/// </summary>
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public IterationStatus Status
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{
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[DebuggerStepThrough]
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get => _status;
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}
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/// <summary>
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/// Resets the <see cref="IterationCountStopCriterion{T}"/> to the pre-calculation state.
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/// </summary>
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public void Reset()
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{
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_status = IterationStatus.Continue;
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}
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/// <summary>
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/// Clones the current <see cref="IterationCountStopCriterion{T}"/> and its settings.
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/// </summary>
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/// <returns>A new instance of the <see cref="IterationCountStopCriterion{T}"/> class.</returns>
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public IIterationStopCriterion<T> Clone()
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{
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return new IterationCountStopCriterion<T>(_maximumNumberOfIterations);
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}
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}
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}
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