LA: iterative solver: delegate stop criterion, e.g. for interactive iteration

src/Numerics/LinearAlgebra/Solvers/DelegateStopCriterion.cs

@@ -0,0 +1,95 @@
+// <copyright file="DelegateStopCriterion.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) 2009-2014 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>
+
+using System;
+
+namespace MathNet.Numerics.LinearAlgebra.Solvers
+{
+    /// <summary>
+    /// Stop criterion that delegates the status determination to a delegate.
+    /// </summary>
+    public class DelegateStopCriterion<T> : IIterationStopCriterion<T>
+        where T : struct, IEquatable<T>, IFormattable
+    {
+        readonly Func<int, Vector<T>, Vector<T>, Vector<T>, IterationStatus> _determine;
+        IterationStatus _status = IterationStatus.Continue;
+
+        /// <summary>
+        /// Create a new instance of this criterion with a custom implementation.
+        /// </summary>
+        /// <param name="determine">Custom implementation with the same signature and semantics as the DetermineStatus method.</param>
+        public DelegateStopCriterion(Func<int, Vector<T>, Vector<T>, Vector<T>, IterationStatus> determine)
+        {
+            _determine = determine;
+        }
+
+        /// <summary>
+        /// Determines the status of the iterative calculation by delegating it to the provided delegate.
+        /// Result is set into <c>Status</c> field.
+        /// </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 stop criteria 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>
+        public IterationStatus DetermineStatus(int iterationNumber, Vector<T> solutionVector, Vector<T> sourceVector, Vector<T> residualVector)
+        {
+            return _status = _determine(iterationNumber, solutionVector, sourceVector, residualVector);
+        }
+
+        /// <summary>
+        /// Gets the current calculation status.
+        /// </summary>
+        public IterationStatus Status
+        {
+            get { return _status; }
+        }
+
+        /// <summary>
+        /// Resets the IIterationStopCriterion to the pre-calculation state.
+        /// </summary>
+        public void Reset()
+        {
+            _status = IterationStatus.Continue;
+        }
+
+        /// <summary>
+        /// Clones this criterion and its settings.
+        /// </summary>
+        public IIterationStopCriterion<T> Clone()
+        {
+            return new DelegateStopCriterion<T>(_determine);
+        }
+    }
+}

src/Numerics/Numerics.csproj

@@ -98,6 +98,7 @@
     <Compile Include="Interpolation\Barycentric.cs" />
     <Compile Include="Interpolation\CubicSpline.cs" />
     <Compile Include="Interpolation\QuadraticSpline.cs" />
+    <Compile Include="LinearAlgebra\Solvers\DelegateStopCriterion.cs" />
     <Compile Include="Precision.Comparison.cs" />
     <Compile Include="Precision.Equality.cs" />
     <Compile Include="Distributions\Bernoulli.cs" />