diff --git a/src/Numerics/Integration/Algorithms/NewtonCotesTrapeziumRule.cs b/src/Numerics/Integration/Algorithms/NewtonCotesTrapeziumRule.cs
index f15efe1d..6b635b3d 100644
--- a/src/Numerics/Integration/Algorithms/NewtonCotesTrapeziumRule.cs
+++ b/src/Numerics/Integration/Algorithms/NewtonCotesTrapeziumRule.cs
@@ -183,66 +183,67 @@ namespace MathNet.Numerics.Integration.Algorithms
             double linearOffset = 0.5 * (intervalEnd + intervalBegin);
             targetRelativeError /= 5 * linearSlope;
 
-            var abcissasIterator = levelAbscissas.GetEnumerator();
-            var weightsIterator = levelWeights.GetEnumerator();
+            using (var abcissasIterator = levelAbscissas.GetEnumerator())
+            using (var weightsIterator = levelWeights.GetEnumerator())
+            {
+                double step = levelOneStep;
 
-            double step = levelOneStep;
+                // First Level
+                abcissasIterator.MoveNext();
+                weightsIterator.MoveNext();
+                double[] abcissasL1 = abcissasIterator.Current;
+                double[] weightsL1 = weightsIterator.Current;
 
-            // First Level
-            abcissasIterator.MoveNext();
-            weightsIterator.MoveNext();
-            double[] abcissasL1 = abcissasIterator.Current;
-            double[] weightsL1 = weightsIterator.Current;
+                double sum = f(linearOffset) * weightsL1[0];
+                for (int i = 1; i < abcissasL1.Length; i++)
+                {
+                    sum += weightsL1[i] * (f((linearSlope * abcissasL1[i]) + linearOffset) + f(-(linearSlope * abcissasL1[i]) + linearOffset));
+                }
 
-            double sum = f(linearOffset) * weightsL1[0];
-            for (int i = 1; i < abcissasL1.Length; i++)
-            {
-                sum += weightsL1[i] * (f((linearSlope * abcissasL1[i]) + linearOffset) + f(-(linearSlope * abcissasL1[i]) + linearOffset));
-            }
+                sum *= step;
 
-            sum *= step;
+                // Additional Levels
+                double previousDelta = double.MaxValue;
+                for (int level = 1; abcissasIterator.MoveNext() && weightsIterator.MoveNext(); level++)
+                {
+                    double[] abcissas = abcissasIterator.Current;
+                    double[] weights = weightsIterator.Current;
 
-            // Additional Levels
-            double previousDelta = double.MaxValue;
-            for (int level = 1; abcissasIterator.MoveNext() && weightsIterator.MoveNext(); level++)
-            {
-                double[] abcissas = abcissasIterator.Current;
-                double[] weights = weightsIterator.Current;
+                    double midpointsum = 0;
+                    for (int i = 0; i < abcissas.Length; i++)
+                    {
+                        midpointsum += weights[i] * (f((linearSlope * abcissas[i]) + linearOffset) + f(-(linearSlope * abcissas[i]) + linearOffset));
+                    }
 
-                double midpointsum = 0;
-                for (int i = 0; i < abcissas.Length; i++)
-                {
-                    midpointsum += weights[i] * (f((linearSlope * abcissas[i]) + linearOffset) + f(-(linearSlope * abcissas[i]) + linearOffset));
-                }
+                    midpointsum *= step;
+                    sum = 0.5 * (sum + midpointsum);
+                    step *= 0.5;
 
-                midpointsum *= step;
-                sum = 0.5 * (sum + midpointsum);
-                step *= 0.5;
+                    double delta = Math.Abs(sum - midpointsum);
 
-                double delta = Math.Abs(sum - midpointsum);
+                    if (level == 1)
+                    {
+                        previousDelta = delta;
+                        continue;
+                    }
 
-                if (level == 1)
-                {
+                    double r = Math.Log(delta) / Math.Log(previousDelta);
                     previousDelta = delta;
-                    continue;
-                }
 
-                double r = Math.Log(delta) / Math.Log(previousDelta);
-                previousDelta = delta;
+                    if (r > 1.9 && r < 2.1)
+                    {
+                        // convergence region
+                        delta = Math.Sqrt(delta);
+                    }
 
-                if (r > 1.9 && r < 2.1)
-                {
-                    // convergence region
-                    delta = Math.Sqrt(delta);
+                    if (sum.AlmostEqualWithRelativeError(midpointsum, delta, targetRelativeError))
+                    {
+                        break;
+                    }
                 }
 
-                if (sum.AlmostEqualWithRelativeError(midpointsum, delta, targetRelativeError))
-                {
-                    break;
-                }
+                return sum * linearSlope;
             }
-
-            return sum * linearSlope;
         }
     }
 }
diff --git a/src/Numerics/LinearAlgebra/Complex/Solvers/Iterator.cs b/src/Numerics/LinearAlgebra/Complex/Solvers/Iterator.cs
index c4c75eeb..3e8916fb 100644
--- a/src/Numerics/LinearAlgebra/Complex/Solvers/Iterator.cs
+++ b/src/Numerics/LinearAlgebra/Complex/Solvers/Iterator.cs
@@ -179,11 +179,11 @@ namespace MathNet.Numerics.LinearAlgebra.Complex.Solvers
         /// Gets an <c>IEnumerator</c> that enumerates over all the stored stop criteria.
         /// </summary>
         /// <remarks>Used for testing only.</remarks>
-        internal IEnumerator<IIterationStopCriterium> StoredStopCriteria
+        internal IEnumerable<IIterationStopCriterium> StoredStopCriteria
         {
             get
             {
-                return _stopCriterias.Select(criterium => criterium.Value).GetEnumerator();
+                return _stopCriterias.Select(criterium => criterium.Value);
             }
         }
 
diff --git a/src/Numerics/LinearAlgebra/Complex32/Solvers/Iterator.cs b/src/Numerics/LinearAlgebra/Complex32/Solvers/Iterator.cs
index 008091fb..3002f188 100644
--- a/src/Numerics/LinearAlgebra/Complex32/Solvers/Iterator.cs
+++ b/src/Numerics/LinearAlgebra/Complex32/Solvers/Iterator.cs
@@ -179,11 +179,11 @@ namespace MathNet.Numerics.LinearAlgebra.Complex32.Solvers
         /// Gets an <c>IEnumerator</c> that enumerates over all the stored stop criteria.
         /// </summary>
         /// <remarks>Used for testing only.</remarks>
-        internal IEnumerator<IIterationStopCriterium> StoredStopCriteria
+        internal IEnumerable<IIterationStopCriterium> StoredStopCriteria
         {
             get
             {
-                return _stopCriterias.Select(criterium => criterium.Value).GetEnumerator();
+                return _stopCriterias.Select(criterium => criterium.Value);
             }
         }
 
diff --git a/src/Numerics/LinearAlgebra/Double/Solvers/Iterator.cs b/src/Numerics/LinearAlgebra/Double/Solvers/Iterator.cs
index 98361b7e..307b41fa 100644
--- a/src/Numerics/LinearAlgebra/Double/Solvers/Iterator.cs
+++ b/src/Numerics/LinearAlgebra/Double/Solvers/Iterator.cs
@@ -179,11 +179,11 @@ namespace MathNet.Numerics.LinearAlgebra.Double.Solvers
         /// Gets an <c>IEnumerator</c> that enumerates over all the stored stop criteria.
         /// </summary>
         /// <remarks>Used for testing only.</remarks>
-        internal IEnumerator<IIterationStopCriterium> StoredStopCriteria
+        internal IEnumerable<IIterationStopCriterium> StoredStopCriteria
         {
             get
             {
-                return _stopCriterias.Select(criterium => criterium.Value).GetEnumerator();
+                return _stopCriterias.Select(criterium => criterium.Value);
             }
         }
 
diff --git a/src/Numerics/LinearAlgebra/Single/Solvers/Iterator.cs b/src/Numerics/LinearAlgebra/Single/Solvers/Iterator.cs
index ad01b5fa..f2fe30c6 100644
--- a/src/Numerics/LinearAlgebra/Single/Solvers/Iterator.cs
+++ b/src/Numerics/LinearAlgebra/Single/Solvers/Iterator.cs
@@ -179,11 +179,11 @@ namespace MathNet.Numerics.LinearAlgebra.Single.Solvers
         /// Gets an <c>IEnumerator</c> that enumerates over all the stored stop criteria.
         /// </summary>
         /// <remarks>Used for testing only.</remarks>
-        internal IEnumerator<IIterationStopCriterium> StoredStopCriteria
+        internal IEnumerable<IIterationStopCriterium> StoredStopCriteria
         {
             get
             {
-                return _stopCriterias.Select(criterium => criterium.Value).GetEnumerator();
+                return _stopCriterias.Select(criterium => criterium.Value);
             }
         }
 
diff --git a/src/Numerics/Statistics/Correlation.cs b/src/Numerics/Statistics/Correlation.cs
index 698ae8c0..e811f1a7 100644
--- a/src/Numerics/Statistics/Correlation.cs
+++ b/src/Numerics/Statistics/Correlation.cs
@@ -49,27 +49,31 @@ namespace MathNet.Numerics.Statistics
         {
             int n = 0;
             double r = 0.0;
+
+            // BUG: PERFORMANCE degraded due to tripple iteration over both IEnumerables
+            
             double meanA = dataA.Mean();
             double meanB = dataB.Mean();
             double sdevA = dataA.StandardDeviation();
             double sdevB = dataB.StandardDeviation();
 
-            IEnumerator<double> ieA = dataA.GetEnumerator();
-            IEnumerator<double> ieB = dataB.GetEnumerator();
-
-            while (ieA.MoveNext())
+            using (IEnumerator<double> ieA = dataA.GetEnumerator())
+            using (IEnumerator<double> ieB = dataB.GetEnumerator())
             {
-                if (ieB.MoveNext() == false)
+                while (ieA.MoveNext())
                 {
-                    throw new ArgumentOutOfRangeException("Datasets dataA and dataB need to have the same length.");
-                }
+                    if (!ieB.MoveNext())
+                    {
+                        throw new ArgumentOutOfRangeException("dataB", "Datasets dataA and dataB need to have the same length. dataB is shorter.");
+                    }
 
-                n++;
-                r += (ieA.Current - meanA) * (ieB.Current - meanB) / (sdevA * sdevB);
-            }
-            if (ieB.MoveNext() == true)
-            {
-                throw new ArgumentOutOfRangeException("Datasets dataA and dataB need to have the same length.");
+                    n++;
+                    r += (ieA.Current - meanA) * (ieB.Current - meanB) / (sdevA * sdevB);
+                }
+                if (ieB.MoveNext())
+                {
+                    throw new ArgumentOutOfRangeException("dataA", "Datasets dataA and dataB need to have the same length. dataA is shorter.");
+                }
             }
 
             return r / (n - 1);
diff --git a/src/Numerics/Statistics/Statistics.cs b/src/Numerics/Statistics/Statistics.cs
index 6b76b6ef..a95c2732 100644
--- a/src/Numerics/Statistics/Statistics.cs
+++ b/src/Numerics/Statistics/Statistics.cs
@@ -102,20 +102,22 @@ namespace MathNet.Numerics.Statistics
             double t = 0;
             ulong j = 0;
 
-            IEnumerator<double> iterator = data.GetEnumerator();
-            if (iterator.MoveNext())
+            using (IEnumerator<double> iterator = data.GetEnumerator())
             {
-                j++;
-                t = iterator.Current;
-            }
+                if (iterator.MoveNext())
+                {
+                    j++;
+                    t = iterator.Current;
+                }
 
-            while (iterator.MoveNext())
-            {
-                j++;
-                double xi = iterator.Current;
-                t += xi;
-                double diff = (j * xi) - t;
-                variance += (diff * diff) / (j * (j - 1));
+                while (iterator.MoveNext())
+                {
+                    j++;
+                    double xi = iterator.Current;
+                    t += xi;
+                    double diff = (j * xi) - t;
+                    variance += (diff * diff) / (j * (j - 1));
+                }
             }
 
             return variance / (j - 1);
@@ -137,33 +139,34 @@ namespace MathNet.Numerics.Statistics
             double t = 0;
             ulong j = 0;
 
-            IEnumerator<double?> iterator = data.GetEnumerator();
-
-            while (true)
+            using (IEnumerator<double?> iterator = data.GetEnumerator())
             {
-                bool hasNext = iterator.MoveNext();
-                if (!hasNext)
+                while (true)
                 {
-                    break;
-                }
+                    bool hasNext = iterator.MoveNext();
+                    if (!hasNext)
+                    {
+                        break;
+                    }
 
-                if (iterator.Current.HasValue)
-                {
-                    j++;
-                    t = iterator.Current.Value;
-                    break;
+                    if (iterator.Current.HasValue)
+                    {
+                        j++;
+                        t = iterator.Current.Value;
+                        break;
+                    }
                 }
-            }
 
-            while (iterator.MoveNext())
-            {
-                if (iterator.Current.HasValue)
+                while (iterator.MoveNext())
                 {
-                    j++;
-                    double xi = iterator.Current.Value;
-                    t += xi;
-                    double diff = (j * xi) - t;
-                    variance += (diff * diff) / (j * (j - 1));
+                    if (iterator.Current.HasValue)
+                    {
+                        j++;
+                        double xi = iterator.Current.Value;
+                        t += xi;
+                        double diff = (j * xi) - t;
+                        variance += (diff * diff) / (j * (j - 1));
+                    }
                 }
             }
 
@@ -186,20 +189,22 @@ namespace MathNet.Numerics.Statistics
             double t = 0;
             ulong j = 0;
 
-            IEnumerator<double> iterator = data.GetEnumerator();
-            if (iterator.MoveNext())
+            using (IEnumerator<double> iterator = data.GetEnumerator())
             {
-                j++;
-                t = iterator.Current;
-            }
+                if (iterator.MoveNext())
+                {
+                    j++;
+                    t = iterator.Current;
+                }
 
-            while (iterator.MoveNext())
-            {
-                j++;
-                double xi = iterator.Current;
-                t += xi;
-                double diff = (j * xi) - t;
-                variance += (diff * diff) / (j * (j - 1));
+                while (iterator.MoveNext())
+                {
+                    j++;
+                    double xi = iterator.Current;
+                    t += xi;
+                    double diff = (j * xi) - t;
+                    variance += (diff * diff) / (j * (j - 1));
+                }
             }
 
             return variance / j;
@@ -221,33 +226,34 @@ namespace MathNet.Numerics.Statistics
             double t = 0;
             ulong j = 0;
 
-            IEnumerator<double?> iterator = data.GetEnumerator();
-
-            while (true)
+            using (IEnumerator<double?> iterator = data.GetEnumerator())
             {
-                bool hasNext = iterator.MoveNext();
-                if (!hasNext)
+                while (true)
                 {
-                    break;
-                }
+                    bool hasNext = iterator.MoveNext();
+                    if (!hasNext)
+                    {
+                        break;
+                    }
 
-                if (iterator.Current.HasValue)
-                {
-                    j++;
-                    t = iterator.Current.Value;
-                    break;
+                    if (iterator.Current.HasValue)
+                    {
+                        j++;
+                        t = iterator.Current.Value;
+                        break;
+                    }
                 }
-            }
 
-            while (iterator.MoveNext())
-            {
-                if (iterator.Current.HasValue)
+                while (iterator.MoveNext())
                 {
-                    j++;
-                    double xi = iterator.Current.Value;
-                    t += xi;
-                    double diff = (j * xi) - t;
-                    variance += (diff * diff) / (j * (j - 1));
+                    if (iterator.Current.HasValue)
+                    {
+                        j++;
+                        double xi = iterator.Current.Value;
+                        t += xi;
+                        double diff = (j * xi) - t;
+                        variance += (diff * diff) / (j * (j - 1));
+                    }
                 }
             }
 
diff --git a/src/UnitTests/LinearAlgebraTests/Complex/DiagonalMatrixTests.cs b/src/UnitTests/LinearAlgebraTests/Complex/DiagonalMatrixTests.cs
index f228ff55..08a78a86 100644
--- a/src/UnitTests/LinearAlgebraTests/Complex/DiagonalMatrixTests.cs
+++ b/src/UnitTests/LinearAlgebraTests/Complex/DiagonalMatrixTests.cs
@@ -536,61 +536,62 @@ namespace MathNet.Numerics.UnitTests.LinearAlgebraTests.Complex
         public override void CanUseIndexedEnumerator()
         {
             var matrix = TestMatrices["Singular3x3"];
-            var enumerator = matrix.IndexedEnumerator().GetEnumerator();
-
-            enumerator.MoveNext();
-            var item = enumerator.Current;
-            Assert.AreEqual(0, item.Item1);
-            Assert.AreEqual(0, item.Item2);
-            Assert.AreEqual(new Complex(1.0, 1.0), item.Item3);
-
-            enumerator.MoveNext();
-            item = enumerator.Current;
-            Assert.AreEqual(0, item.Item1);
-            Assert.AreEqual(1, item.Item2);
-            Assert.AreEqual(Complex.Zero, item.Item3);
-
-            enumerator.MoveNext();
-            item = enumerator.Current;
-            Assert.AreEqual(0, item.Item1);
-            Assert.AreEqual(2, item.Item2);
-            Assert.AreEqual(Complex.Zero, item.Item3);
-
-            enumerator.MoveNext();
-            item = enumerator.Current;
-            Assert.AreEqual(1, item.Item1);
-            Assert.AreEqual(0, item.Item2);
-            Assert.AreEqual(Complex.Zero, item.Item3);
-
-            enumerator.MoveNext();
-            item = enumerator.Current;
-            Assert.AreEqual(1, item.Item1);
-            Assert.AreEqual(1, item.Item2);
-            Assert.AreEqual(Complex.Zero, item.Item3);
-
-            enumerator.MoveNext();
-            item = enumerator.Current;
-            Assert.AreEqual(1, item.Item1);
-            Assert.AreEqual(2, item.Item2);
-            Assert.AreEqual(Complex.Zero, item.Item3);
-
-            enumerator.MoveNext();
-            item = enumerator.Current;
-            Assert.AreEqual(2, item.Item1);
-            Assert.AreEqual(0, item.Item2);
-            Assert.AreEqual(Complex.Zero, item.Item3);
-
-            enumerator.MoveNext();
-            item = enumerator.Current;
-            Assert.AreEqual(2, item.Item1);
-            Assert.AreEqual(1, item.Item2);
-            Assert.AreEqual(Complex.Zero, item.Item3);
-
-            enumerator.MoveNext();
-            item = enumerator.Current;
-            Assert.AreEqual(2, item.Item1);
-            Assert.AreEqual(2, item.Item2);
-            Assert.AreEqual(new Complex(3.0, 1.0), item.Item3);
+            using (var enumerator = matrix.IndexedEnumerator().GetEnumerator())
+            {
+                enumerator.MoveNext();
+                var item = enumerator.Current;
+                Assert.AreEqual(0, item.Item1);
+                Assert.AreEqual(0, item.Item2);
+                Assert.AreEqual(new Complex(1.0, 1.0), item.Item3);
+
+                enumerator.MoveNext();
+                item = enumerator.Current;
+                Assert.AreEqual(0, item.Item1);
+                Assert.AreEqual(1, item.Item2);
+                Assert.AreEqual(Complex.Zero, item.Item3);
+
+                enumerator.MoveNext();
+                item = enumerator.Current;
+                Assert.AreEqual(0, item.Item1);
+                Assert.AreEqual(2, item.Item2);
+                Assert.AreEqual(Complex.Zero, item.Item3);
+
+                enumerator.MoveNext();
+                item = enumerator.Current;
+                Assert.AreEqual(1, item.Item1);
+                Assert.AreEqual(0, item.Item2);
+                Assert.AreEqual(Complex.Zero, item.Item3);
+
+                enumerator.MoveNext();
+                item = enumerator.Current;
+                Assert.AreEqual(1, item.Item1);
+                Assert.AreEqual(1, item.Item2);
+                Assert.AreEqual(Complex.Zero, item.Item3);
+
+                enumerator.MoveNext();
+                item = enumerator.Current;
+                Assert.AreEqual(1, item.Item1);
+                Assert.AreEqual(2, item.Item2);
+                Assert.AreEqual(Complex.Zero, item.Item3);
+
+                enumerator.MoveNext();
+                item = enumerator.Current;
+                Assert.AreEqual(2, item.Item1);
+                Assert.AreEqual(0, item.Item2);
+                Assert.AreEqual(Complex.Zero, item.Item3);
+
+                enumerator.MoveNext();
+                item = enumerator.Current;
+                Assert.AreEqual(2, item.Item1);
+                Assert.AreEqual(1, item.Item2);
+                Assert.AreEqual(Complex.Zero, item.Item3);
+
+                enumerator.MoveNext();
+                item = enumerator.Current;
+                Assert.AreEqual(2, item.Item1);
+                Assert.AreEqual(2, item.Item2);
+                Assert.AreEqual(new Complex(3.0, 1.0), item.Item3);
+            }
         }
 
         /// <summary>
diff --git a/src/UnitTests/LinearAlgebraTests/Complex/MatrixTests.cs b/src/UnitTests/LinearAlgebraTests/Complex/MatrixTests.cs
index a5abd476..4e6a54ba 100644
--- a/src/UnitTests/LinearAlgebraTests/Complex/MatrixTests.cs
+++ b/src/UnitTests/LinearAlgebraTests/Complex/MatrixTests.cs
@@ -1893,61 +1893,62 @@ namespace MathNet.Numerics.UnitTests.LinearAlgebraTests.Complex
         public virtual void CanUseIndexedEnumerator()
         {
             var matrix = TestMatrices["Singular3x3"];
-            var enumerator = matrix.IndexedEnumerator().GetEnumerator();
-
-            enumerator.MoveNext();
-            var item = enumerator.Current;
-            Assert.AreEqual(0, item.Item1);
-            Assert.AreEqual(0, item.Item2);
-            Assert.AreEqual(new Complex(1.0, 1.0), item.Item3);
-
-            enumerator.MoveNext();
-            item = enumerator.Current;
-            Assert.AreEqual(0, item.Item1);
-            Assert.AreEqual(1, item.Item2);
-            Assert.AreEqual(new Complex(1.0, 1.0), item.Item3);
-
-            enumerator.MoveNext();
-            item = enumerator.Current;
-            Assert.AreEqual(0, item.Item1);
-            Assert.AreEqual(2, item.Item2);
-            Assert.AreEqual(new Complex(2.0, 1.0), item.Item3);
-
-            enumerator.MoveNext();
-            item = enumerator.Current;
-            Assert.AreEqual(1, item.Item1);
-            Assert.AreEqual(0, item.Item2);
-            Assert.AreEqual(new Complex(1.0, 1.0), item.Item3);
-
-            enumerator.MoveNext();
-            item = enumerator.Current;
-            Assert.AreEqual(1, item.Item1);
-            Assert.AreEqual(1, item.Item2);
-            Assert.AreEqual(new Complex(1.0, 1.0), item.Item3);
-
-            enumerator.MoveNext();
-            item = enumerator.Current;
-            Assert.AreEqual(1, item.Item1);
-            Assert.AreEqual(2, item.Item2);
-            Assert.AreEqual(new Complex(2.0, 1.0), item.Item3);
-
-            enumerator.MoveNext();
-            item = enumerator.Current;
-            Assert.AreEqual(2, item.Item1);
-            Assert.AreEqual(0, item.Item2);
-            Assert.AreEqual(new Complex(1.0, 1.0), item.Item3);
-
-            enumerator.MoveNext();
-            item = enumerator.Current;
-            Assert.AreEqual(2, item.Item1);
-            Assert.AreEqual(1, item.Item2);
-            Assert.AreEqual(new Complex(1.0, 1.0), item.Item3);
-
-            enumerator.MoveNext();
-            item = enumerator.Current;
-            Assert.AreEqual(2, item.Item1);
-            Assert.AreEqual(2, item.Item2);
-            Assert.AreEqual(new Complex(2.0, 1.0), item.Item3);
+            using (var enumerator = matrix.IndexedEnumerator().GetEnumerator())
+            {
+                enumerator.MoveNext();
+                var item = enumerator.Current;
+                Assert.AreEqual(0, item.Item1);
+                Assert.AreEqual(0, item.Item2);
+                Assert.AreEqual(new Complex(1.0, 1.0), item.Item3);
+
+                enumerator.MoveNext();
+                item = enumerator.Current;
+                Assert.AreEqual(0, item.Item1);
+                Assert.AreEqual(1, item.Item2);
+                Assert.AreEqual(new Complex(1.0, 1.0), item.Item3);
+
+                enumerator.MoveNext();
+                item = enumerator.Current;
+                Assert.AreEqual(0, item.Item1);
+                Assert.AreEqual(2, item.Item2);
+                Assert.AreEqual(new Complex(2.0, 1.0), item.Item3);
+
+                enumerator.MoveNext();
+                item = enumerator.Current;
+                Assert.AreEqual(1, item.Item1);
+                Assert.AreEqual(0, item.Item2);
+                Assert.AreEqual(new Complex(1.0, 1.0), item.Item3);
+
+                enumerator.MoveNext();
+                item = enumerator.Current;
+                Assert.AreEqual(1, item.Item1);
+                Assert.AreEqual(1, item.Item2);
+                Assert.AreEqual(new Complex(1.0, 1.0), item.Item3);
+
+                enumerator.MoveNext();
+                item = enumerator.Current;
+                Assert.AreEqual(1, item.Item1);
+                Assert.AreEqual(2, item.Item2);
+                Assert.AreEqual(new Complex(2.0, 1.0), item.Item3);
+
+                enumerator.MoveNext();
+                item = enumerator.Current;
+                Assert.AreEqual(2, item.Item1);
+                Assert.AreEqual(0, item.Item2);
+                Assert.AreEqual(new Complex(1.0, 1.0), item.Item3);
+
+                enumerator.MoveNext();
+                item = enumerator.Current;
+                Assert.AreEqual(2, item.Item1);
+                Assert.AreEqual(1, item.Item2);
+                Assert.AreEqual(new Complex(1.0, 1.0), item.Item3);
+
+                enumerator.MoveNext();
+                item = enumerator.Current;
+                Assert.AreEqual(2, item.Item1);
+                Assert.AreEqual(2, item.Item2);
+                Assert.AreEqual(new Complex(2.0, 1.0), item.Item3);
+            }
         }
 
         /// <summary>
diff --git a/src/UnitTests/LinearAlgebraTests/Complex/Solvers/IteratorTest.cs b/src/UnitTests/LinearAlgebraTests/Complex/Solvers/IteratorTest.cs
index e15ff400..76136223 100644
--- a/src/UnitTests/LinearAlgebraTests/Complex/Solvers/IteratorTest.cs
+++ b/src/UnitTests/LinearAlgebraTests/Complex/Solvers/IteratorTest.cs
@@ -104,10 +104,8 @@ namespace MathNet.Numerics.UnitTests.LinearAlgebraTests.Complex.Solvers
 
             // Check that we have all the criteria
             Assert.AreEqual(criteria.Count, iterator.NumberOfCriteria, "Incorrect criterium count");
-            var enumerator = iterator.StoredStopCriteria;
-            while (enumerator.MoveNext())
+            foreach (var criterium in iterator.StoredStopCriteria)
             {
-                var criterium = enumerator.Current;
                 Assert.IsTrue(criteria.Exists(c => ReferenceEquals(c, criterium)), "Criterium missing");
             }
         }
@@ -159,10 +157,8 @@ namespace MathNet.Numerics.UnitTests.LinearAlgebraTests.Complex.Solvers
 
             // Check that we have all the criteria
             Assert.AreEqual(criteria.Count, iterator.NumberOfCriteria, "Incorrect criterium count");
-            var enumerator = iterator.StoredStopCriteria;
-            while (enumerator.MoveNext())
+            foreach (var criterium in iterator.StoredStopCriteria)
             {
-                var criterium = enumerator.Current;
                 Assert.IsTrue(criteria.Exists(c => ReferenceEquals(c, criterium)), "Criterium missing");
             }
         }
@@ -418,11 +414,9 @@ namespace MathNet.Numerics.UnitTests.LinearAlgebraTests.Complex.Solvers
             Assert.AreEqual(iterator.NumberOfCriteria, clone.NumberOfCriteria, "Incorrect criterium count");
 
             // ReSharper restore PossibleNullReferenceException
-            var enumerator = clone.StoredStopCriteria;
-            while (enumerator.MoveNext())
+            foreach (var criterium in clone.StoredStopCriteria)
             {
-                var criterium = enumerator.Current;
-                Assert.IsTrue(criteria.Exists(c => c.GetType().Equals(criterium.GetType())), "Criterium missing");
+                Assert.IsTrue(criteria.Exists(c => c.GetType() == criterium.GetType()), "Criterium missing");
             }
         }
     }
diff --git a/src/UnitTests/LinearAlgebraTests/Complex32/DiagonalMatrixTests.cs b/src/UnitTests/LinearAlgebraTests/Complex32/DiagonalMatrixTests.cs
index e789e8f1..008a6147 100644
--- a/src/UnitTests/LinearAlgebraTests/Complex32/DiagonalMatrixTests.cs
+++ b/src/UnitTests/LinearAlgebraTests/Complex32/DiagonalMatrixTests.cs
@@ -536,61 +536,62 @@ namespace MathNet.Numerics.UnitTests.LinearAlgebraTests.Complex32
         public override void CanUseIndexedEnumerator()
         {
             var matrix = TestMatrices["Singular3x3"];
-            var enumerator = matrix.IndexedEnumerator().GetEnumerator();
-
-            enumerator.MoveNext();
-            var item = enumerator.Current;
-            Assert.AreEqual(0, item.Item1);
-            Assert.AreEqual(0, item.Item2);
-            Assert.AreEqual(new Complex32(1.0f, 1.0f), item.Item3);
-
-            enumerator.MoveNext();
-            item = enumerator.Current;
-            Assert.AreEqual(0, item.Item1);
-            Assert.AreEqual(1, item.Item2);
-            Assert.AreEqual(Complex32.Zero, item.Item3);
-
-            enumerator.MoveNext();
-            item = enumerator.Current;
-            Assert.AreEqual(0, item.Item1);
-            Assert.AreEqual(2, item.Item2);
-            Assert.AreEqual(Complex32.Zero, item.Item3);
-
-            enumerator.MoveNext();
-            item = enumerator.Current;
-            Assert.AreEqual(1, item.Item1);
-            Assert.AreEqual(0, item.Item2);
-            Assert.AreEqual(Complex32.Zero, item.Item3);
-
-            enumerator.MoveNext();
-            item = enumerator.Current;
-            Assert.AreEqual(1, item.Item1);
-            Assert.AreEqual(1, item.Item2);
-            Assert.AreEqual(Complex32.Zero, item.Item3);
-
-            enumerator.MoveNext();
-            item = enumerator.Current;
-            Assert.AreEqual(1, item.Item1);
-            Assert.AreEqual(2, item.Item2);
-            Assert.AreEqual(Complex32.Zero, item.Item3);
-
-            enumerator.MoveNext();
-            item = enumerator.Current;
-            Assert.AreEqual(2, item.Item1);
-            Assert.AreEqual(0, item.Item2);
-            Assert.AreEqual(Complex32.Zero, item.Item3);
-
-            enumerator.MoveNext();
-            item = enumerator.Current;
-            Assert.AreEqual(2, item.Item1);
-            Assert.AreEqual(1, item.Item2);
-            Assert.AreEqual(Complex32.Zero, item.Item3);
-
-            enumerator.MoveNext();
-            item = enumerator.Current;
-            Assert.AreEqual(2, item.Item1);
-            Assert.AreEqual(2, item.Item2);
-            Assert.AreEqual(new Complex32(3.0f, 1.0f), item.Item3);
+            using (var enumerator = matrix.IndexedEnumerator().GetEnumerator())
+            {
+                enumerator.MoveNext();
+                var item = enumerator.Current;
+                Assert.AreEqual(0, item.Item1);
+                Assert.AreEqual(0, item.Item2);
+                Assert.AreEqual(new Complex32(1.0f, 1.0f), item.Item3);
+
+                enumerator.MoveNext();
+                item = enumerator.Current;
+                Assert.AreEqual(0, item.Item1);
+                Assert.AreEqual(1, item.Item2);
+                Assert.AreEqual(Complex32.Zero, item.Item3);
+
+                enumerator.MoveNext();
+                item = enumerator.Current;
+                Assert.AreEqual(0, item.Item1);
+                Assert.AreEqual(2, item.Item2);
+                Assert.AreEqual(Complex32.Zero, item.Item3);
+
+                enumerator.MoveNext();
+                item = enumerator.Current;
+                Assert.AreEqual(1, item.Item1);
+                Assert.AreEqual(0, item.Item2);
+                Assert.AreEqual(Complex32.Zero, item.Item3);
+
+                enumerator.MoveNext();
+                item = enumerator.Current;
+                Assert.AreEqual(1, item.Item1);
+                Assert.AreEqual(1, item.Item2);
+                Assert.AreEqual(Complex32.Zero, item.Item3);
+
+                enumerator.MoveNext();
+                item = enumerator.Current;
+                Assert.AreEqual(1, item.Item1);
+                Assert.AreEqual(2, item.Item2);
+                Assert.AreEqual(Complex32.Zero, item.Item3);
+
+                enumerator.MoveNext();
+                item = enumerator.Current;
+                Assert.AreEqual(2, item.Item1);
+                Assert.AreEqual(0, item.Item2);
+                Assert.AreEqual(Complex32.Zero, item.Item3);
+
+                enumerator.MoveNext();
+                item = enumerator.Current;
+                Assert.AreEqual(2, item.Item1);
+                Assert.AreEqual(1, item.Item2);
+                Assert.AreEqual(Complex32.Zero, item.Item3);
+
+                enumerator.MoveNext();
+                item = enumerator.Current;
+                Assert.AreEqual(2, item.Item1);
+                Assert.AreEqual(2, item.Item2);
+                Assert.AreEqual(new Complex32(3.0f, 1.0f), item.Item3);
+            }
         }
 
         /// <summary>
diff --git a/src/UnitTests/LinearAlgebraTests/Complex32/MatrixTests.cs b/src/UnitTests/LinearAlgebraTests/Complex32/MatrixTests.cs
index 59f831e8..58952d08 100644
--- a/src/UnitTests/LinearAlgebraTests/Complex32/MatrixTests.cs
+++ b/src/UnitTests/LinearAlgebraTests/Complex32/MatrixTests.cs
@@ -1893,61 +1893,62 @@ namespace MathNet.Numerics.UnitTests.LinearAlgebraTests.Complex32
         public virtual void CanUseIndexedEnumerator()
         {
             var matrix = TestMatrices["Singular3x3"];
-            var enumerator = matrix.IndexedEnumerator().GetEnumerator();
-
-            enumerator.MoveNext();
-            var item = enumerator.Current;
-            Assert.AreEqual(0, item.Item1);
-            Assert.AreEqual(0, item.Item2);
-            Assert.AreEqual(new Complex32(1.0f, 1.0f), item.Item3);
-
-            enumerator.MoveNext();
-            item = enumerator.Current;
-            Assert.AreEqual(0, item.Item1);
-            Assert.AreEqual(1, item.Item2);
-            Assert.AreEqual(new Complex32(1.0f, 1.0f), item.Item3);
-
-            enumerator.MoveNext();
-            item = enumerator.Current;
-            Assert.AreEqual(0, item.Item1);
-            Assert.AreEqual(2, item.Item2);
-            Assert.AreEqual(new Complex32(2.0f, 1.0f), item.Item3);
-
-            enumerator.MoveNext();
-            item = enumerator.Current;
-            Assert.AreEqual(1, item.Item1);
-            Assert.AreEqual(0, item.Item2);
-            Assert.AreEqual(new Complex32(1.0f, 1.0f), item.Item3);
-
-            enumerator.MoveNext();
-            item = enumerator.Current;
-            Assert.AreEqual(1, item.Item1);
-            Assert.AreEqual(1, item.Item2);
-            Assert.AreEqual(new Complex32(1.0f, 1.0f), item.Item3);
-
-            enumerator.MoveNext();
-            item = enumerator.Current;
-            Assert.AreEqual(1, item.Item1);
-            Assert.AreEqual(2, item.Item2);
-            Assert.AreEqual(new Complex32(2.0f, 1.0f), item.Item3);
-
-            enumerator.MoveNext();
-            item = enumerator.Current;
-            Assert.AreEqual(2, item.Item1);
-            Assert.AreEqual(0, item.Item2);
-            Assert.AreEqual(new Complex32(1.0f, 1.0f), item.Item3);
-
-            enumerator.MoveNext();
-            item = enumerator.Current;
-            Assert.AreEqual(2, item.Item1);
-            Assert.AreEqual(1, item.Item2);
-            Assert.AreEqual(new Complex32(1.0f, 1.0f), item.Item3);
-
-            enumerator.MoveNext();
-            item = enumerator.Current;
-            Assert.AreEqual(2, item.Item1);
-            Assert.AreEqual(2, item.Item2);
-            Assert.AreEqual(new Complex32(2.0f, 1.0f), item.Item3);
+            using (var enumerator = matrix.IndexedEnumerator().GetEnumerator())
+            {
+                enumerator.MoveNext();
+                var item = enumerator.Current;
+                Assert.AreEqual(0, item.Item1);
+                Assert.AreEqual(0, item.Item2);
+                Assert.AreEqual(new Complex32(1.0f, 1.0f), item.Item3);
+
+                enumerator.MoveNext();
+                item = enumerator.Current;
+                Assert.AreEqual(0, item.Item1);
+                Assert.AreEqual(1, item.Item2);
+                Assert.AreEqual(new Complex32(1.0f, 1.0f), item.Item3);
+
+                enumerator.MoveNext();
+                item = enumerator.Current;
+                Assert.AreEqual(0, item.Item1);
+                Assert.AreEqual(2, item.Item2);
+                Assert.AreEqual(new Complex32(2.0f, 1.0f), item.Item3);
+
+                enumerator.MoveNext();
+                item = enumerator.Current;
+                Assert.AreEqual(1, item.Item1);
+                Assert.AreEqual(0, item.Item2);
+                Assert.AreEqual(new Complex32(1.0f, 1.0f), item.Item3);
+
+                enumerator.MoveNext();
+                item = enumerator.Current;
+                Assert.AreEqual(1, item.Item1);
+                Assert.AreEqual(1, item.Item2);
+                Assert.AreEqual(new Complex32(1.0f, 1.0f), item.Item3);
+
+                enumerator.MoveNext();
+                item = enumerator.Current;
+                Assert.AreEqual(1, item.Item1);
+                Assert.AreEqual(2, item.Item2);
+                Assert.AreEqual(new Complex32(2.0f, 1.0f), item.Item3);
+
+                enumerator.MoveNext();
+                item = enumerator.Current;
+                Assert.AreEqual(2, item.Item1);
+                Assert.AreEqual(0, item.Item2);
+                Assert.AreEqual(new Complex32(1.0f, 1.0f), item.Item3);
+
+                enumerator.MoveNext();
+                item = enumerator.Current;
+                Assert.AreEqual(2, item.Item1);
+                Assert.AreEqual(1, item.Item2);
+                Assert.AreEqual(new Complex32(1.0f, 1.0f), item.Item3);
+
+                enumerator.MoveNext();
+                item = enumerator.Current;
+                Assert.AreEqual(2, item.Item1);
+                Assert.AreEqual(2, item.Item2);
+                Assert.AreEqual(new Complex32(2.0f, 1.0f), item.Item3);
+            }
         }
 
         /// <summary>
diff --git a/src/UnitTests/LinearAlgebraTests/Complex32/Solvers/IteratorTest.cs b/src/UnitTests/LinearAlgebraTests/Complex32/Solvers/IteratorTest.cs
index 72db8743..160c7f66 100644
--- a/src/UnitTests/LinearAlgebraTests/Complex32/Solvers/IteratorTest.cs
+++ b/src/UnitTests/LinearAlgebraTests/Complex32/Solvers/IteratorTest.cs
@@ -103,10 +103,8 @@ namespace MathNet.Numerics.UnitTests.LinearAlgebraTests.Complex32.Solvers
 
             // Check that we have all the criteria
             Assert.AreEqual(criteria.Count, iterator.NumberOfCriteria, "Incorrect criterium count");
-            var enumerator = iterator.StoredStopCriteria;
-            while (enumerator.MoveNext())
+            foreach (var criterium in iterator.StoredStopCriteria)
             {
-                var criterium = enumerator.Current;
                 Assert.IsTrue(criteria.Exists(c => ReferenceEquals(c, criterium)), "Criterium missing");
             }
         }
@@ -158,10 +156,8 @@ namespace MathNet.Numerics.UnitTests.LinearAlgebraTests.Complex32.Solvers
 
             // Check that we have all the criteria
             Assert.AreEqual(criteria.Count, iterator.NumberOfCriteria, "Incorrect criterium count");
-            var enumerator = iterator.StoredStopCriteria;
-            while (enumerator.MoveNext())
+            foreach (var criterium in iterator.StoredStopCriteria)
             {
-                var criterium = enumerator.Current;
                 Assert.IsTrue(criteria.Exists(c => ReferenceEquals(c, criterium)), "Criterium missing");
             }
         }
@@ -417,11 +413,9 @@ namespace MathNet.Numerics.UnitTests.LinearAlgebraTests.Complex32.Solvers
             Assert.AreEqual(iterator.NumberOfCriteria, clone.NumberOfCriteria, "Incorrect criterium count");
 
             // ReSharper restore PossibleNullReferenceException
-            var enumerator = clone.StoredStopCriteria;
-            while (enumerator.MoveNext())
+            foreach (var criterium in clone.StoredStopCriteria)
             {
-                var criterium = enumerator.Current;
-                Assert.IsTrue(criteria.Exists(c => c.GetType().Equals(criterium.GetType())), "Criterium missing");
+                Assert.IsTrue(criteria.Exists(c => c.GetType() == criterium.GetType()), "Criterium missing");
             }
         }
     }
diff --git a/src/UnitTests/LinearAlgebraTests/Double/DiagonalMatrixTests.cs b/src/UnitTests/LinearAlgebraTests/Double/DiagonalMatrixTests.cs
index d14d2951..60431a41 100644
--- a/src/UnitTests/LinearAlgebraTests/Double/DiagonalMatrixTests.cs
+++ b/src/UnitTests/LinearAlgebraTests/Double/DiagonalMatrixTests.cs
@@ -536,61 +536,62 @@ namespace MathNet.Numerics.UnitTests.LinearAlgebraTests.Double
         public override void CanUseIndexedEnumerator()
         {
             var matrix = TestMatrices["Singular3x3"];
-            var enumerator = matrix.IndexedEnumerator().GetEnumerator();
-
-            enumerator.MoveNext();
-            var item = enumerator.Current;
-            Assert.AreEqual(0, item.Item1);
-            Assert.AreEqual(0, item.Item2);
-            Assert.AreEqual(1.0, item.Item3);
-
-            enumerator.MoveNext();
-            item = enumerator.Current;
-            Assert.AreEqual(0, item.Item1);
-            Assert.AreEqual(1, item.Item2);
-            Assert.AreEqual(0.0, item.Item3);
-
-            enumerator.MoveNext();
-            item = enumerator.Current;
-            Assert.AreEqual(0, item.Item1);
-            Assert.AreEqual(2, item.Item2);
-            Assert.AreEqual(0.0, item.Item3);
-
-            enumerator.MoveNext();
-            item = enumerator.Current;
-            Assert.AreEqual(1, item.Item1);
-            Assert.AreEqual(0, item.Item2);
-            Assert.AreEqual(0.0, item.Item3);
-
-            enumerator.MoveNext();
-            item = enumerator.Current;
-            Assert.AreEqual(1, item.Item1);
-            Assert.AreEqual(1, item.Item2);
-            Assert.AreEqual(0.0, item.Item3);
-
-            enumerator.MoveNext();
-            item = enumerator.Current;
-            Assert.AreEqual(1, item.Item1);
-            Assert.AreEqual(2, item.Item2);
-            Assert.AreEqual(0.0, item.Item3);
-
-            enumerator.MoveNext();
-            item = enumerator.Current;
-            Assert.AreEqual(2, item.Item1);
-            Assert.AreEqual(0, item.Item2);
-            Assert.AreEqual(0.0, item.Item3);
-
-            enumerator.MoveNext();
-            item = enumerator.Current;
-            Assert.AreEqual(2, item.Item1);
-            Assert.AreEqual(1, item.Item2);
-            Assert.AreEqual(0.0, item.Item3);
-
-            enumerator.MoveNext();
-            item = enumerator.Current;
-            Assert.AreEqual(2, item.Item1);
-            Assert.AreEqual(2, item.Item2);
-            Assert.AreEqual(3.0, item.Item3);
+            using (var enumerator = matrix.IndexedEnumerator().GetEnumerator())
+            {
+                enumerator.MoveNext();
+                var item = enumerator.Current;
+                Assert.AreEqual(0, item.Item1);
+                Assert.AreEqual(0, item.Item2);
+                Assert.AreEqual(1.0, item.Item3);
+
+                enumerator.MoveNext();
+                item = enumerator.Current;
+                Assert.AreEqual(0, item.Item1);
+                Assert.AreEqual(1, item.Item2);
+                Assert.AreEqual(0.0, item.Item3);
+
+                enumerator.MoveNext();
+                item = enumerator.Current;
+                Assert.AreEqual(0, item.Item1);
+                Assert.AreEqual(2, item.Item2);
+                Assert.AreEqual(0.0, item.Item3);
+
+                enumerator.MoveNext();
+                item = enumerator.Current;
+                Assert.AreEqual(1, item.Item1);
+                Assert.AreEqual(0, item.Item2);
+                Assert.AreEqual(0.0, item.Item3);
+
+                enumerator.MoveNext();
+                item = enumerator.Current;
+                Assert.AreEqual(1, item.Item1);
+                Assert.AreEqual(1, item.Item2);
+                Assert.AreEqual(0.0, item.Item3);
+
+                enumerator.MoveNext();
+                item = enumerator.Current;
+                Assert.AreEqual(1, item.Item1);
+                Assert.AreEqual(2, item.Item2);
+                Assert.AreEqual(0.0, item.Item3);
+
+                enumerator.MoveNext();
+                item = enumerator.Current;
+                Assert.AreEqual(2, item.Item1);
+                Assert.AreEqual(0, item.Item2);
+                Assert.AreEqual(0.0, item.Item3);
+
+                enumerator.MoveNext();
+                item = enumerator.Current;
+                Assert.AreEqual(2, item.Item1);
+                Assert.AreEqual(1, item.Item2);
+                Assert.AreEqual(0.0, item.Item3);
+
+                enumerator.MoveNext();
+                item = enumerator.Current;
+                Assert.AreEqual(2, item.Item1);
+                Assert.AreEqual(2, item.Item2);
+                Assert.AreEqual(3.0, item.Item3);
+            }
         }
 
         /// <summary>
diff --git a/src/UnitTests/LinearAlgebraTests/Double/MatrixTests.cs b/src/UnitTests/LinearAlgebraTests/Double/MatrixTests.cs
index f942a87c..45c04cd5 100644
--- a/src/UnitTests/LinearAlgebraTests/Double/MatrixTests.cs
+++ b/src/UnitTests/LinearAlgebraTests/Double/MatrixTests.cs
@@ -1830,61 +1830,62 @@ namespace MathNet.Numerics.UnitTests.LinearAlgebraTests.Double
         public virtual void CanUseIndexedEnumerator()
         {
             var matrix = TestMatrices["Singular3x3"];
-            var enumerator = matrix.IndexedEnumerator().GetEnumerator();
-
-            enumerator.MoveNext();
-            var item = enumerator.Current;
-            Assert.AreEqual(0, item.Item1);
-            Assert.AreEqual(0, item.Item2);
-            Assert.AreEqual(1.0, item.Item3);
-
-            enumerator.MoveNext();
-            item = enumerator.Current;
-            Assert.AreEqual(0, item.Item1);
-            Assert.AreEqual(1, item.Item2);
-            Assert.AreEqual(1.0, item.Item3);
-
-            enumerator.MoveNext();
-            item = enumerator.Current;
-            Assert.AreEqual(0, item.Item1);
-            Assert.AreEqual(2, item.Item2);
-            Assert.AreEqual(2.0, item.Item3);
-
-            enumerator.MoveNext();
-            item = enumerator.Current;
-            Assert.AreEqual(1, item.Item1);
-            Assert.AreEqual(0, item.Item2);
-            Assert.AreEqual(1.0, item.Item3);
-
-            enumerator.MoveNext();
-            item = enumerator.Current;
-            Assert.AreEqual(1, item.Item1);
-            Assert.AreEqual(1, item.Item2);
-            Assert.AreEqual(1.0, item.Item3);
-
-            enumerator.MoveNext();
-            item = enumerator.Current;
-            Assert.AreEqual(1, item.Item1);
-            Assert.AreEqual(2, item.Item2);
-            Assert.AreEqual(2.0, item.Item3);
-
-            enumerator.MoveNext();
-            item = enumerator.Current;
-            Assert.AreEqual(2, item.Item1);
-            Assert.AreEqual(0, item.Item2);
-            Assert.AreEqual(1.0, item.Item3);
-
-            enumerator.MoveNext();
-            item = enumerator.Current;
-            Assert.AreEqual(2, item.Item1);
-            Assert.AreEqual(1, item.Item2);
-            Assert.AreEqual(1.0, item.Item3);
-
-            enumerator.MoveNext();
-            item = enumerator.Current;
-            Assert.AreEqual(2, item.Item1);
-            Assert.AreEqual(2, item.Item2);
-            Assert.AreEqual(2.0, item.Item3);
+            using (var enumerator = matrix.IndexedEnumerator().GetEnumerator())
+            {
+                enumerator.MoveNext();
+                var item = enumerator.Current;
+                Assert.AreEqual(0, item.Item1);
+                Assert.AreEqual(0, item.Item2);
+                Assert.AreEqual(1.0, item.Item3);
+
+                enumerator.MoveNext();
+                item = enumerator.Current;
+                Assert.AreEqual(0, item.Item1);
+                Assert.AreEqual(1, item.Item2);
+                Assert.AreEqual(1.0, item.Item3);
+
+                enumerator.MoveNext();
+                item = enumerator.Current;
+                Assert.AreEqual(0, item.Item1);
+                Assert.AreEqual(2, item.Item2);
+                Assert.AreEqual(2.0, item.Item3);
+
+                enumerator.MoveNext();
+                item = enumerator.Current;
+                Assert.AreEqual(1, item.Item1);
+                Assert.AreEqual(0, item.Item2);
+                Assert.AreEqual(1.0, item.Item3);
+
+                enumerator.MoveNext();
+                item = enumerator.Current;
+                Assert.AreEqual(1, item.Item1);
+                Assert.AreEqual(1, item.Item2);
+                Assert.AreEqual(1.0, item.Item3);
+
+                enumerator.MoveNext();
+                item = enumerator.Current;
+                Assert.AreEqual(1, item.Item1);
+                Assert.AreEqual(2, item.Item2);
+                Assert.AreEqual(2.0, item.Item3);
+
+                enumerator.MoveNext();
+                item = enumerator.Current;
+                Assert.AreEqual(2, item.Item1);
+                Assert.AreEqual(0, item.Item2);
+                Assert.AreEqual(1.0, item.Item3);
+
+                enumerator.MoveNext();
+                item = enumerator.Current;
+                Assert.AreEqual(2, item.Item1);
+                Assert.AreEqual(1, item.Item2);
+                Assert.AreEqual(1.0, item.Item3);
+
+                enumerator.MoveNext();
+                item = enumerator.Current;
+                Assert.AreEqual(2, item.Item1);
+                Assert.AreEqual(2, item.Item2);
+                Assert.AreEqual(2.0, item.Item3);
+            }
         }
 
         /// <summary>
diff --git a/src/UnitTests/LinearAlgebraTests/Double/Solvers/IteratorTest.cs b/src/UnitTests/LinearAlgebraTests/Double/Solvers/IteratorTest.cs
index a6387579..8c068825 100644
--- a/src/UnitTests/LinearAlgebraTests/Double/Solvers/IteratorTest.cs
+++ b/src/UnitTests/LinearAlgebraTests/Double/Solvers/IteratorTest.cs
@@ -104,10 +104,8 @@ namespace MathNet.Numerics.UnitTests.LinearAlgebraTests.Double.Solvers
 
             // Check that we have all the criteria
             Assert.AreEqual(criteria.Count, iterator.NumberOfCriteria, "Incorrect criterium count");
-            var enumerator = iterator.StoredStopCriteria;
-            while (enumerator.MoveNext())
+            foreach (var criterium in iterator.StoredStopCriteria)
             {
-                var criterium = enumerator.Current;
                 Assert.IsTrue(criteria.Exists(c => ReferenceEquals(c, criterium)), "Criterium missing");
             }
         }
@@ -159,10 +157,8 @@ namespace MathNet.Numerics.UnitTests.LinearAlgebraTests.Double.Solvers
 
             // Check that we have all the criteria
             Assert.AreEqual(criteria.Count, iterator.NumberOfCriteria, "Incorrect criterium count");
-            var enumerator = iterator.StoredStopCriteria;
-            while (enumerator.MoveNext())
+            foreach (var criterium in iterator.StoredStopCriteria)
             {
-                var criterium = enumerator.Current;
                 Assert.IsTrue(criteria.Exists(c => ReferenceEquals(c, criterium)), "Criterium missing");
             }
         }
@@ -418,10 +414,8 @@ namespace MathNet.Numerics.UnitTests.LinearAlgebraTests.Double.Solvers
             Assert.AreEqual(iterator.NumberOfCriteria, clone.NumberOfCriteria, "Incorrect criterium count");
 
             // ReSharper restore PossibleNullReferenceException
-            var enumerator = clone.StoredStopCriteria;
-            while (enumerator.MoveNext())
+            foreach (var criterium in clone.StoredStopCriteria)
             {
-                var criterium = enumerator.Current;
                 Assert.IsTrue(criteria.Exists(c => c.GetType().Equals(criterium.GetType())), "Criterium missing");
             }
         }
diff --git a/src/UnitTests/LinearAlgebraTests/Single/DiagonalMatrixTests.cs b/src/UnitTests/LinearAlgebraTests/Single/DiagonalMatrixTests.cs
index 831a9fd0..207ef2e1 100644
--- a/src/UnitTests/LinearAlgebraTests/Single/DiagonalMatrixTests.cs
+++ b/src/UnitTests/LinearAlgebraTests/Single/DiagonalMatrixTests.cs
@@ -535,61 +535,63 @@ namespace MathNet.Numerics.UnitTests.LinearAlgebraTests.Single
         public override void CanUseIndexedEnumerator()
         {
             var matrix = TestMatrices["Singular3x3"];
-            var enumerator = matrix.IndexedEnumerator().GetEnumerator();
-
-            enumerator.MoveNext();
-            var item = enumerator.Current;
-            Assert.AreEqual(0, item.Item1);
-            Assert.AreEqual(0, item.Item2);
-            Assert.AreEqual(1.0f, item.Item3);
-
-            enumerator.MoveNext();
-            item = enumerator.Current;
-            Assert.AreEqual(0, item.Item1);
-            Assert.AreEqual(1, item.Item2);
-            Assert.AreEqual(0.0f, item.Item3);
-
-            enumerator.MoveNext();
-            item = enumerator.Current;
-            Assert.AreEqual(0, item.Item1);
-            Assert.AreEqual(2, item.Item2);
-            Assert.AreEqual(0.0f, item.Item3);
-
-            enumerator.MoveNext();
-            item = enumerator.Current;
-            Assert.AreEqual(1, item.Item1);
-            Assert.AreEqual(0, item.Item2);
-            Assert.AreEqual(0.0f, item.Item3);
-
-            enumerator.MoveNext();
-            item = enumerator.Current;
-            Assert.AreEqual(1, item.Item1);
-            Assert.AreEqual(1, item.Item2);
-            Assert.AreEqual(0.0f, item.Item3);
-
-            enumerator.MoveNext();
-            item = enumerator.Current;
-            Assert.AreEqual(1, item.Item1);
-            Assert.AreEqual(2, item.Item2);
-            Assert.AreEqual(0.0f, item.Item3);
-
-            enumerator.MoveNext();
-            item = enumerator.Current;
-            Assert.AreEqual(2, item.Item1);
-            Assert.AreEqual(0, item.Item2);
-            Assert.AreEqual(0.0f, item.Item3);
-
-            enumerator.MoveNext();
-            item = enumerator.Current;
-            Assert.AreEqual(2, item.Item1);
-            Assert.AreEqual(1, item.Item2);
-            Assert.AreEqual(0.0f, item.Item3);
-
-            enumerator.MoveNext();
-            item = enumerator.Current;
-            Assert.AreEqual(2, item.Item1);
-            Assert.AreEqual(2, item.Item2);
-            Assert.AreEqual(3.0f, item.Item3);
+            using (var enumerator = matrix.IndexedEnumerator().GetEnumerator())
+            {
+                enumerator.MoveNext();
+                var item = enumerator.Current;
+                Assert.AreEqual(0, item.Item1);
+                Assert.AreEqual(0, item.Item2);
+                Assert.AreEqual(1.0f, item.Item3);
+
+                enumerator.MoveNext();
+                item = enumerator.Current;
+                Assert.AreEqual(0, item.Item1);
+                Assert.AreEqual(1, item.Item2);
+                Assert.AreEqual(0.0f, item.Item3);
+
+                enumerator.MoveNext();
+                item = enumerator.Current;
+                Assert.AreEqual(0, item.Item1);
+                Assert.AreEqual(2, item.Item2);
+                Assert.AreEqual(0.0f, item.Item3);
+
+                enumerator.MoveNext();
+                item = enumerator.Current;
+                Assert.AreEqual(1, item.Item1);
+                Assert.AreEqual(0, item.Item2);
+                Assert.AreEqual(0.0f, item.Item3);
+
+                enumerator.MoveNext();
+                item = enumerator.Current;
+                Assert.AreEqual(1, item.Item1);
+                Assert.AreEqual(1, item.Item2);
+                Assert.AreEqual(0.0f, item.Item3);
+
+                enumerator.MoveNext();
+                item = enumerator.Current;
+                Assert.AreEqual(1, item.Item1);
+                Assert.AreEqual(2, item.Item2);
+                Assert.AreEqual(0.0f, item.Item3);
+
+                enumerator.MoveNext();
+                item = enumerator.Current;
+                Assert.AreEqual(2, item.Item1);
+                Assert.AreEqual(0, item.Item2);
+                Assert.AreEqual(0.0f, item.Item3);
+
+                enumerator.MoveNext();
+                item = enumerator.Current;
+                Assert.AreEqual(2, item.Item1);
+                Assert.AreEqual(1, item.Item2);
+                Assert.AreEqual(0.0f, item.Item3);
+
+                enumerator.MoveNext();
+                item = enumerator.Current;
+            
+                Assert.AreEqual(2, item.Item1);
+                Assert.AreEqual(2, item.Item2);
+                Assert.AreEqual(3.0f, item.Item3);
+            }
         }
 
         /// <summary>
diff --git a/src/UnitTests/LinearAlgebraTests/Single/MatrixTests.cs b/src/UnitTests/LinearAlgebraTests/Single/MatrixTests.cs
index 6eb5e632..c7dd7b7a 100644
--- a/src/UnitTests/LinearAlgebraTests/Single/MatrixTests.cs
+++ b/src/UnitTests/LinearAlgebraTests/Single/MatrixTests.cs
@@ -1830,61 +1830,62 @@ namespace MathNet.Numerics.UnitTests.LinearAlgebraTests.Single
         public virtual void CanUseIndexedEnumerator()
         {
             var matrix = TestMatrices["Singular3x3"];
-            var enumerator = matrix.IndexedEnumerator().GetEnumerator();
-
-            enumerator.MoveNext();
-            var item = enumerator.Current;
-            Assert.AreEqual(0, item.Item1);
-            Assert.AreEqual(0, item.Item2);
-            Assert.AreEqual(1.0f, item.Item3);
-
-            enumerator.MoveNext();
-            item = enumerator.Current;
-            Assert.AreEqual(0, item.Item1);
-            Assert.AreEqual(1, item.Item2);
-            Assert.AreEqual(1.0f, item.Item3);
-
-            enumerator.MoveNext();
-            item = enumerator.Current;
-            Assert.AreEqual(0, item.Item1);
-            Assert.AreEqual(2, item.Item2);
-            Assert.AreEqual(2.0f, item.Item3);
-
-            enumerator.MoveNext();
-            item = enumerator.Current;
-            Assert.AreEqual(1, item.Item1);
-            Assert.AreEqual(0, item.Item2);
-            Assert.AreEqual(1.0f, item.Item3);
-
-            enumerator.MoveNext();
-            item = enumerator.Current;
-            Assert.AreEqual(1, item.Item1);
-            Assert.AreEqual(1, item.Item2);
-            Assert.AreEqual(1.0f, item.Item3);
-
-            enumerator.MoveNext();
-            item = enumerator.Current;
-            Assert.AreEqual(1, item.Item1);
-            Assert.AreEqual(2, item.Item2);
-            Assert.AreEqual(2.0f, item.Item3);
-
-            enumerator.MoveNext();
-            item = enumerator.Current;
-            Assert.AreEqual(2, item.Item1);
-            Assert.AreEqual(0, item.Item2);
-            Assert.AreEqual(1.0f, item.Item3);
-
-            enumerator.MoveNext();
-            item = enumerator.Current;
-            Assert.AreEqual(2, item.Item1);
-            Assert.AreEqual(1, item.Item2);
-            Assert.AreEqual(1.0f, item.Item3);
-
-            enumerator.MoveNext();
-            item = enumerator.Current;
-            Assert.AreEqual(2, item.Item1);
-            Assert.AreEqual(2, item.Item2);
-            Assert.AreEqual(2.0f, item.Item3);
+            using (var enumerator = matrix.IndexedEnumerator().GetEnumerator())
+            {
+                enumerator.MoveNext();
+                var item = enumerator.Current;
+                Assert.AreEqual(0, item.Item1);
+                Assert.AreEqual(0, item.Item2);
+                Assert.AreEqual(1.0f, item.Item3);
+
+                enumerator.MoveNext();
+                item = enumerator.Current;
+                Assert.AreEqual(0, item.Item1);
+                Assert.AreEqual(1, item.Item2);
+                Assert.AreEqual(1.0f, item.Item3);
+
+                enumerator.MoveNext();
+                item = enumerator.Current;
+                Assert.AreEqual(0, item.Item1);
+                Assert.AreEqual(2, item.Item2);
+                Assert.AreEqual(2.0f, item.Item3);
+
+                enumerator.MoveNext();
+                item = enumerator.Current;
+                Assert.AreEqual(1, item.Item1);
+                Assert.AreEqual(0, item.Item2);
+                Assert.AreEqual(1.0f, item.Item3);
+
+                enumerator.MoveNext();
+                item = enumerator.Current;
+                Assert.AreEqual(1, item.Item1);
+                Assert.AreEqual(1, item.Item2);
+                Assert.AreEqual(1.0f, item.Item3);
+
+                enumerator.MoveNext();
+                item = enumerator.Current;
+                Assert.AreEqual(1, item.Item1);
+                Assert.AreEqual(2, item.Item2);
+                Assert.AreEqual(2.0f, item.Item3);
+
+                enumerator.MoveNext();
+                item = enumerator.Current;
+                Assert.AreEqual(2, item.Item1);
+                Assert.AreEqual(0, item.Item2);
+                Assert.AreEqual(1.0f, item.Item3);
+
+                enumerator.MoveNext();
+                item = enumerator.Current;
+                Assert.AreEqual(2, item.Item1);
+                Assert.AreEqual(1, item.Item2);
+                Assert.AreEqual(1.0f, item.Item3);
+
+                enumerator.MoveNext();
+                item = enumerator.Current;
+                Assert.AreEqual(2, item.Item1);
+                Assert.AreEqual(2, item.Item2);
+                Assert.AreEqual(2.0f, item.Item3);
+            }
         }
 
         /// <summary>
diff --git a/src/UnitTests/LinearAlgebraTests/Single/Solvers/IteratorTest.cs b/src/UnitTests/LinearAlgebraTests/Single/Solvers/IteratorTest.cs
index e425e839..dfbef20a 100644
--- a/src/UnitTests/LinearAlgebraTests/Single/Solvers/IteratorTest.cs
+++ b/src/UnitTests/LinearAlgebraTests/Single/Solvers/IteratorTest.cs
@@ -103,10 +103,8 @@ namespace MathNet.Numerics.UnitTests.LinearAlgebraTests.Single.Solvers
 
             // Check that we have all the criteria
             Assert.AreEqual(criteria.Count, iterator.NumberOfCriteria, "Incorrect criterium count");
-            var enumerator = iterator.StoredStopCriteria;
-            while (enumerator.MoveNext())
+            foreach (var criterium in iterator.StoredStopCriteria)
             {
-                var criterium = enumerator.Current;
                 Assert.IsTrue(criteria.Exists(c => ReferenceEquals(c, criterium)), "Criterium missing");
             }
         }
@@ -158,10 +156,8 @@ namespace MathNet.Numerics.UnitTests.LinearAlgebraTests.Single.Solvers
 
             // Check that we have all the criteria
             Assert.AreEqual(criteria.Count, iterator.NumberOfCriteria, "Incorrect criterium count");
-            var enumerator = iterator.StoredStopCriteria;
-            while (enumerator.MoveNext())
+            foreach (var criterium in iterator.StoredStopCriteria)
             {
-                var criterium = enumerator.Current;
                 Assert.IsTrue(criteria.Exists(c => ReferenceEquals(c, criterium)), "Criterium missing");
             }
         }
@@ -417,11 +413,9 @@ namespace MathNet.Numerics.UnitTests.LinearAlgebraTests.Single.Solvers
             Assert.AreEqual(iterator.NumberOfCriteria, clone.NumberOfCriteria, "Incorrect criterium count");
 
             // ReSharper restore PossibleNullReferenceException
-            var enumerator = clone.StoredStopCriteria;
-            while (enumerator.MoveNext())
+            foreach (var criterium in clone.StoredStopCriteria)
             {
-                var criterium = enumerator.Current;
-                Assert.IsTrue(criteria.Exists(c => c.GetType().Equals(criterium.GetType())), "Criterium missing");
+                Assert.IsTrue(criteria.Exists(c => c.GetType() == criterium.GetType()), "Criterium missing");
             }
         }
     }