From 7dac174cfe0bf62c9c5809921d498f4e98009967 Mon Sep 17 00:00:00 2001
From: Christoph Ruegg <git@cdrnet.ch>
Date: Tue, 17 Sep 2013 00:13:27 +0200
Subject: [PATCH] LA: new iterative solver cancellation stop criterium

---
 .../Solvers/CancellationStopCriterium.cs      | 115 ++++++++++++++++++
 src/Numerics/Numerics.csproj                  |   1 +
 2 files changed, 116 insertions(+)
 create mode 100644 src/Numerics/LinearAlgebra/Solvers/CancellationStopCriterium.cs

diff --git a/src/Numerics/LinearAlgebra/Solvers/CancellationStopCriterium.cs b/src/Numerics/LinearAlgebra/Solvers/CancellationStopCriterium.cs
new file mode 100644
index 00000000..a9b97c60
--- /dev/null
+++ b/src/Numerics/LinearAlgebra/Solvers/CancellationStopCriterium.cs
@@ -0,0 +1,115 @@
+// <copyright file="IterationCountStopCriterium.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) 2009-2013 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;
+using System.Diagnostics;
+using System.Threading;
+
+namespace MathNet.Numerics.LinearAlgebra.Solvers
+{
+    /// <summary>
+    /// Defines an <see cref="IIterationStopCriterium{T}"/> that uses a cancellationn token as stop criterium.
+    /// </summary>
+    public sealed class CancellationStopCriterium<T> : IIterationStopCriterium<T> where T : struct, IEquatable<T>, IFormattable
+    {
+        readonly CancellationToken _masterToken;
+        CancellationTokenSource _currentTcs;
+
+        /// <summary>
+        /// Initializes a new instance of the <see cref="IterationCountStopCriterium{T}"/> class.
+        /// </summary>
+        public CancellationStopCriterium()
+        {
+            _masterToken = CancellationToken.None;
+            _currentTcs = CancellationTokenSource.CreateLinkedTokenSource(CancellationToken.None);
+        }
+
+        /// <summary>
+        /// Initializes a new instance of the <see cref="IterationCountStopCriterium{T}"/> class.
+        /// </summary>
+        public CancellationStopCriterium(CancellationToken masterToken)
+        {
+            _masterToken = masterToken;
+            _currentTcs = CancellationTokenSource.CreateLinkedTokenSource(masterToken);
+        }
+
+        /// <summary>
+        /// Determines the status of the iterative calculation based on the stop criteria stored
+        /// by the current <see cref="IterationCountStopCriterium{T}"/>. 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 _currentTcs.Token.IsCancellationRequested ? IterationStatus.Cancelled : IterationStatus.Running;
+        }
+
+        /// <summary>
+        /// Gets the current calculation status.
+        /// </summary>
+        public IterationStatus Status
+        {
+            [DebuggerStepThrough]
+            get
+            {
+                return _currentTcs.Token.IsCancellationRequested ? IterationStatus.Cancelled : IterationStatus.Running;
+            }
+        }
+
+        public void Cancel()
+        {
+            _currentTcs.Cancel();
+        }
+
+        /// <summary>
+        /// Resets the <see cref="IterationCountStopCriterium{T}"/> to the pre-calculation state.
+        /// </summary>
+        public void Reset()
+        {
+            _currentTcs = CancellationTokenSource.CreateLinkedTokenSource(_masterToken);
+        }
+
+        /// <summary>
+        /// Clones the current <see cref="IterationCountStopCriterium{T}"/> and its settings.
+        /// </summary>
+        /// <returns>A new instance of the <see cref="IterationCountStopCriterium{T}"/> class.</returns>
+        public IIterationStopCriterium<T> Clone()
+        {
+            return new CancellationStopCriterium<T>(_masterToken);
+        }
+    }
+}
diff --git a/src/Numerics/Numerics.csproj b/src/Numerics/Numerics.csproj
index 1703403c..a2a08745 100644
--- a/src/Numerics/Numerics.csproj
+++ b/src/Numerics/Numerics.csproj
@@ -123,6 +123,7 @@
     <Compile Include="Distributions\Zipf.cs" />
     <Compile Include="LinearAlgebra\Builder.cs" />
     <Compile Include="LinearAlgebra\Matrix.Factorization.cs" />
+    <Compile Include="LinearAlgebra\Solvers\CancellationStopCriterium.cs" />
     <Compile Include="LinearAlgebra\Solvers\IterationStatus.cs" />
     <Compile Include="LinearAlgebra\Solvers\Iterator.cs" />
     <Compile Include="LinearAlgebra\Solvers\IterationCountStopCriterium.cs" />