mathnet-numerics/src/Numerics/LinearAlgebra/Generic/Solvers/IIterator.cs

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namespace MathNet.Numerics.LinearAlgebra.Generic.Solvers
{
    using System;
    using System.Numerics;
    using Status;
    using StopCriterium;

    /// <summary>
    /// Defines the base interface for iterators that help control an iterative calculation.
    /// </summary>
    /// <typeparam name="T">Supported data types are double, single, <see cref="Complex"/>, and <see cref="Complex32"/>.</typeparam>
    public interface IIterator<T>
#if !SILVERLIGHT
    : ICloneable
#endif
    where T : struct, IEquatable<T>, IFormattable
    {
        /// <summary>
        /// Adds an <see cref="IIterationStopCriterium{T}"/> to the internal collection of stop-criteria. Only a 
        /// single stop criterium of each type can be stored.
        /// </summary>
        /// <param name="stopCriterium">The stop criterium to add.</param>
        /// <exception cref="ArgumentNullException">Thrown if <paramref name="stopCriterium"/> is <see langword="null" />.</exception>
        /// <exception cref="ArgumentException">Thrown if <paramref name="stopCriterium"/> is of the same type as an already stored criterium.</exception>
        void Add(IIterationStopCriterium<T> stopCriterium);

        /// <summary>
        /// Removes the <see cref="IIterationStopCriterium{T}"/> from the internal collection.
        /// </summary>
        /// <param name="stopCriterium">The stop criterium that must be removed.</param>
        void Remove(IIterationStopCriterium<T> stopCriterium);

        /// <summary>
        /// Indicates if the specific stop criterium is stored by the <see cref="IIterator{T}"/>.
        /// </summary>
        /// <param name="stopCriterium">The stop criterium.</param>
        /// <returns><c>true</c> if the <see cref="IIterator{T}"/> contains the stop criterium; otherwise <c>false</c>.</returns>
        bool Contains(IIterationStopCriterium<T> stopCriterium);

        /// <summary>
        /// Indicates to the iterator that the iterative process has been cancelled.
        /// </summary>
        /// <remarks>Does not reset the stop-criteria.</remarks>
        void IterationCancelled();

        /// <summary>
        /// Determines the status of the iterative calculation based on the stop criteria stored
        /// by the current <see cref="IIterator{T}"/>.  Status is set to <c>Status</c> field of current object.
        /// </summary>
        /// <param name="iterationNumber">The number of iterations that have passed so far.</param>
        /// <param name="solutionVector">The vector containing the current solution values.</param>
        /// <param name="sourceVector">The right hand side vector.</param>
        /// <param name="residualVector">The vector containing the current residual vectors.</param>
        /// <remarks>
        /// The individual iterators may internally track the progress of the calculation based
        /// on the invocation of this method. Therefore this method should only be called if the 
        /// calculation has moved forwards at least one step.
        /// </remarks>
        void DetermineStatus(int iterationNumber, Vector<T> solutionVector, Vector<T> sourceVector, Vector<T> residualVector);

        /// <summary>
        /// Gets the current calculation status.
        /// </summary>
        /// <remarks><see langword="null" /> is not a legal value. Status should be set in <see cref="DetermineStatus"/> implementation.</remarks>.
        ICalculationStatus Status { get; }

        /// <summary>
        /// Resets the <see cref="IIterator{T}"/> to the pre-calculation state.
        /// </summary>
        /// <remarks>
        /// Note to implementers: Invoking this method should not clear the user defined
        /// property values, only the state that is used to track the progress of the 
        /// calculation.
        /// </remarks>
        void ResetToPrecalculationState();

#if SILVERLIGHT
        IIterator<double> Clone();
#endif
    }
}