diff --git a/CHANGELOG.md b/CHANGELOG.md
index 045a391..bc3bab2 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,3 +1,7 @@
+### Version 4.4.0 - 2026-06-10
+
+* Add Refactorize methods to SparseCholesky, SparseLDL and SparseLU
+
 ### Version 4.3.0 - 2025-11-11
 
 * Add net10.0 and remove net6.0 target framework.
diff --git a/CSparse.Tests/CSparse.Tests.csproj b/CSparse.Tests/CSparse.Tests.csproj
index a795c2b..e4cb7b0 100644
--- a/CSparse.Tests/CSparse.Tests.csproj
+++ b/CSparse.Tests/CSparse.Tests.csproj
@@ -41,9 +41,9 @@
   </ItemGroup>
 
   <ItemGroup>
-    <PackageReference Include="NUnit" Version="4.4.0" />
-    <PackageReference Include="NUnit3TestAdapter" Version="5.2.0" />
-    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="18.0.0" />
+    <PackageReference Include="NUnit" Version="4.6.1" />
+    <PackageReference Include="NUnit3TestAdapter" Version="6.2.0" />
+    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="18.6.0" />
   </ItemGroup>
 
   <ItemGroup>
diff --git a/CSparse.Tests/Complex/ComplexNumberComparer.cs b/CSparse.Tests/Complex/ComplexNumberComparer.cs
index 0a98cdd..ab2adce 100644
--- a/CSparse.Tests/Complex/ComplexNumberComparer.cs
+++ b/CSparse.Tests/Complex/ComplexNumberComparer.cs
@@ -11,7 +11,7 @@ namespace CSparse.Tests.Complex
 
     public class ComplexNumberComparer : IComparer, IComparer<Complex>
     {
-        public static ComplexNumberComparer Default = new ComplexNumberComparer();
+        public static ComplexNumberComparer Default = new();
 
         // Floating point tolerance
         const double TOL = 1e-8;
diff --git a/CSparse.Tests/Complex/MatrixHelper.cs b/CSparse.Tests/Complex/MatrixHelper.cs
index db1081d..b5dfdc6 100644
--- a/CSparse.Tests/Complex/MatrixHelper.cs
+++ b/CSparse.Tests/Complex/MatrixHelper.cs
@@ -4,22 +4,18 @@ namespace CSparse.Tests.Complex
     using CSparse.Storage;
     using System.Collections.Generic;
     using System.IO;
-    using System.Linq;
     using System.Numerics;
 
     class MatrixHelper
     {
-        private static Dictionary<string, DenseTestData<Complex>> dense = new Dictionary<string, DenseTestData<Complex>>();
-
-        private static Dictionary<string, SparseTestData<Complex>> sparse = new Dictionary<string, SparseTestData<Complex>>();
+        private static readonly Dictionary<string, DenseTestData<Complex>> dense = [];
+        private static readonly Dictionary<string, SparseTestData<Complex>> sparse = [];
 
         public static SparseTestData<Complex> LoadSparse(int rows, int columns)
         {
             string resource = string.Format("test-data-dense-{0}x{1}.txt", rows, columns);
 
-            SparseTestData<Complex> data;
-
-            if (!sparse.TryGetValue(resource, out data))
+            if (!sparse.TryGetValue(resource, out SparseTestData<Complex> data))
             {
                 var dense = LoadDense(rows, columns);
 
@@ -35,9 +31,7 @@ public static DenseTestData<Complex> LoadDense(int rows, int columns)
         {
             string resource = string.Format("test-data-dense-{0}x{1}.txt", rows, columns);
 
-            DenseTestData<Complex> data;
-
-            if (!dense.TryGetValue(resource, out data))
+            if (!dense.TryGetValue(resource, out DenseTestData<Complex> data))
             {
                 var stream = ResourceLoader.GetStream(resource, "Double");
 
@@ -53,22 +47,21 @@ private static DenseTestData<Complex> ReadDenseTestData(Stream stream)
         {
             var data = Tests.Double.DenseTestDataReader.Read(stream);
 
-            var result = new DenseTestData<Complex>();
-
-            result.A = ToComplex(data.A);
-            result.B = ToComplex(data.B);
-            result.x = ToComplex(data.x);
-            result.y = ToComplex(data.y);
-            result.AT = ToComplex(data.AT);
-            result.BT = ToComplex(data.BT);
-            result.ApB = ToComplex(data.ApB);
-            result.AmBT = ToComplex(data.AmBT);
-            result.ATmB = ToComplex(data.ATmB);
-            result.Ax = ToComplex(data.Ax);
-            result.ATy = ToComplex(data.ATy);
-            result.xTBT = ToComplex(data.xTBT);
-
-            return result;
+            return new DenseTestData<Complex>
+            {
+                A = ToComplex(data.A),
+                B = ToComplex(data.B),
+                x = ToComplex(data.x),
+                y = ToComplex(data.y),
+                AT = ToComplex(data.AT),
+                BT = ToComplex(data.BT),
+                ApB = ToComplex(data.ApB),
+                AmBT = ToComplex(data.AmBT),
+                ATmB = ToComplex(data.ATmB),
+                Ax = ToComplex(data.Ax),
+                ATy = ToComplex(data.ATy),
+                xTBT = ToComplex(data.xTBT)
+            };
         }
 
         private static Complex[] ToComplex(double[] vec)
@@ -101,26 +94,23 @@ private static DenseColumnMajorStorage<Complex> ToComplex(DenseColumnMajorStorag
 
         private static SparseTestData<Complex> DenseToSparse(DenseTestData<Complex> dense)
         {
-            var data = new SparseTestData<Complex>()
+            return new SparseTestData<Complex>
             {
                 RowCount = dense.RowCount,
-                ColumnCount = dense.ColumnCount
+                ColumnCount = dense.ColumnCount,
+                A = DenseToSparse(dense.A),
+                B = DenseToSparse(dense.B),
+                x = dense.x,
+                y = dense.y,
+                AT = DenseToSparse(dense.AT),
+                BT = DenseToSparse(dense.BT),
+                ApB = DenseToSparse(dense.ApB),
+                AmBT = DenseToSparse(dense.AmBT),
+                ATmB = DenseToSparse(dense.ATmB),
+                Ax = dense.Ax,
+                ATy = dense.ATy,
+                xTBT = dense.xTBT
             };
-
-            data.A = DenseToSparse(dense.A);
-            data.B = DenseToSparse(dense.B);
-            data.x = dense.x;
-            data.y = dense.y;
-            data.AT = DenseToSparse(dense.AT);
-            data.BT = DenseToSparse(dense.BT);
-            data.ApB = DenseToSparse(dense.ApB);
-            data.AmBT = DenseToSparse(dense.AmBT);
-            data.ATmB = DenseToSparse(dense.ATmB);
-            data.Ax = dense.Ax;
-            data.ATy = dense.ATy;
-            data.xTBT = dense.xTBT;
-
-            return data;
         }
 
         private static CompressedColumnStorage<Complex> DenseToSparse(DenseColumnMajorStorage<Complex> dense)
diff --git a/CSparse.Tests/Double/DenseTestDataReader.cs b/CSparse.Tests/Double/DenseTestDataReader.cs
index 72b99b5..06504c7 100644
--- a/CSparse.Tests/Double/DenseTestDataReader.cs
+++ b/CSparse.Tests/Double/DenseTestDataReader.cs
@@ -9,80 +9,77 @@ class DenseTestDataReader
     {
         public static DenseTestData<double> Read(Stream stream)
         {
-            using (var reader = new StreamReader(stream))
+            using var reader = new StreamReader(stream);
+
+            string line = reader.ReadLine();
+
+            GetItem(line, out string name, out string value);
+
+            if (name != "size")
             {
-                string line, name, value;
+                throw new FormatException("Expected first line = size.");
+            }
 
-                line = reader.ReadLine();
+            var data = ReadSize(value);
 
+            int m = data.RowCount;
+            int n = data.ColumnCount;
+
+            while ((line = reader.ReadLine()) != null)
+            {
                 GetItem(line, out name, out value);
 
-                if (name != "size")
+                if (name == "A")
                 {
-                    throw new FormatException("Expected first line = size.");
+                    data.A = ReadMatrix(value, m, n);
                 }
-
-                var data = ReadSize(value);
-
-                int m = data.RowCount;
-                int n = data.ColumnCount;
-
-                while ((line = reader.ReadLine()) != null)
+                else if (name == "B")
                 {
-                    GetItem(line, out name, out value);
-
-                    if (name == "A")
-                    {
-                        data.A = ReadMatrix(value, m, n);
-                    }
-                    else if (name == "B")
-                    {
-                        data.B = ReadMatrix(value, m, n);
-                    }
-                    else if (name == "x")
-                    {
-                        data.x = ReadVector(value, n);
-                    }
-                    else if (name == "y")
-                    {
-                        data.y = ReadVector(value, m);
-                    }
-                    else if (name == "A'")
-                    {
-                        data.AT = ReadMatrix(value, n, m);
-                    }
-                    else if (name == "B'")
-                    {
-                        data.BT = ReadMatrix(value, n, m);
-                    }
-                    else if (name == "A+B")
-                    {
-                        data.ApB = ReadMatrix(value, m, n);
-                    }
-                    else if (name == "A*B'")
-                    {
-                        data.AmBT = ReadMatrix(value, m, m);
-                    }
-                    else if (name == "A'*B")
-                    {
-                        data.ATmB = ReadMatrix(value, n, n);
-                    }
-                    else if (name == "A*x")
-                    {
-                        data.Ax = ReadVector(value, m);
-                    }
-                    else if (name == "A'*y")
-                    {
-                        data.ATy = ReadVector(value, n);
-                    }
-                    else if (name == "x'*B'")
-                    {
-                        data.xTBT = ReadVector(value, m);
-                    }
+                    data.B = ReadMatrix(value, m, n);
+                }
+                else if (name == "x")
+                {
+                    data.x = ReadVector(value, n);
+                }
+                else if (name == "y")
+                {
+                    data.y = ReadVector(value, m);
+                }
+                else if (name == "A'")
+                {
+                    data.AT = ReadMatrix(value, n, m);
+                }
+                else if (name == "B'")
+                {
+                    data.BT = ReadMatrix(value, n, m);
+                }
+                else if (name == "A+B")
+                {
+                    data.ApB = ReadMatrix(value, m, n);
+                }
+                else if (name == "A*B'")
+                {
+                    data.AmBT = ReadMatrix(value, m, m);
+                }
+                else if (name == "A'*B")
+                {
+                    data.ATmB = ReadMatrix(value, n, n);
+                }
+                else if (name == "A*x")
+                {
+                    data.Ax = ReadVector(value, m);
+                }
+                else if (name == "A'*y")
+                {
+                    data.ATy = ReadVector(value, n);
+                }
+                else if (name == "x'*B'")
+                {
+                    data.xTBT = ReadVector(value, m);
                 }
-
-                return data;
             }
+
+            return data;
         }
 
         private static void GetItem(string line, out string name, out string value)
diff --git a/CSparse.Tests/Double/MatrixHelper.cs b/CSparse.Tests/Double/MatrixHelper.cs
index a2cff13..363332d 100644
--- a/CSparse.Tests/Double/MatrixHelper.cs
+++ b/CSparse.Tests/Double/MatrixHelper.cs
@@ -5,17 +5,14 @@ namespace CSparse.Tests.Double
 
     class MatrixHelper
     {
-        private static Dictionary<string, DenseTestData<double>> dense = new Dictionary<string, DenseTestData<double>>();
-
-        private static Dictionary<string, SparseTestData<double>> sparse = new Dictionary<string, SparseTestData<double>>();
+        private static readonly Dictionary<string, DenseTestData<double>> dense = [];
+        private static readonly Dictionary<string, SparseTestData<double>> sparse = [];
 
         public static SparseTestData<double> LoadSparse(int rows, int columns)
         {
             string resource = string.Format("test-data-dense-{0}x{1}.txt", rows, columns);
 
-            SparseTestData<double> data;
-
-            if (!sparse.TryGetValue(resource, out data))
+            if (!sparse.TryGetValue(resource, out SparseTestData<double> data))
             {
                 var dense = LoadDense(rows, columns);
 
@@ -31,9 +28,7 @@ public static DenseTestData<double> LoadDense(int rows, int columns)
         {
             string resource = string.Format("test-data-dense-{0}x{1}.txt", rows, columns);
 
-            DenseTestData<double> data;
-
-            if (!dense.TryGetValue(resource, out data))
+            if (!dense.TryGetValue(resource, out DenseTestData<double> data))
             {
                 var stream = ResourceLoader.GetStream(resource, "Double");
 
@@ -47,26 +42,23 @@ public static DenseTestData<double> LoadDense(int rows, int columns)
 
         private static SparseTestData<double> DenseToSparse(DenseTestData<double> dense)
         {
-            var data = new SparseTestData<double>()
+            return new SparseTestData<double>
             {
                 RowCount = dense.RowCount,
-                ColumnCount = dense.ColumnCount
+                ColumnCount = dense.ColumnCount,
+                A = DenseToSparse(dense.A),
+                B = DenseToSparse(dense.B),
+                x = dense.x,
+                y = dense.y,
+                AT = DenseToSparse(dense.AT),
+                BT = DenseToSparse(dense.BT),
+                ApB = DenseToSparse(dense.ApB),
+                AmBT = DenseToSparse(dense.AmBT),
+                ATmB = DenseToSparse(dense.ATmB),
+                Ax = dense.Ax,
+                ATy = dense.ATy,
+                xTBT = dense.xTBT
             };
-
-            data.A = DenseToSparse(dense.A);
-            data.B = DenseToSparse(dense.B);
-            data.x = dense.x;
-            data.y = dense.y;
-            data.AT = DenseToSparse(dense.AT);
-            data.BT = DenseToSparse(dense.BT);
-            data.ApB = DenseToSparse(dense.ApB);
-            data.AmBT = DenseToSparse(dense.AmBT);
-            data.ATmB = DenseToSparse(dense.ATmB);
-            data.Ax = dense.Ax;
-            data.ATy = dense.ATy;
-            data.xTBT = dense.xTBT;
-
-            return data;
         }
 
         private static CompressedColumnStorage<double> DenseToSparse(DenseColumnMajorStorage<double> dense)
diff --git a/CSparse.Tests/IO/TestMatrixMarketReader.cs b/CSparse.Tests/IO/TestMatrixMarketReader.cs
index 0a26212..d7edfcb 100644
--- a/CSparse.Tests/IO/TestMatrixMarketReader.cs
+++ b/CSparse.Tests/IO/TestMatrixMarketReader.cs
@@ -10,35 +10,31 @@ public class TestMatrixMarketReader
         [Test]
         public void TestSymmetric()
         {
-            var stream = ResourceLoader.GetStream("LFAT5.mtx", "Double");
+            using var stream = ResourceLoader.GetStream("LFAT5.mtx", "Double");
+            using var reader = new StreamReader(stream);
 
-            using (var reader = new StreamReader(stream))
-            {
-                var A = MatrixMarketReader.ReadStorage<double>(reader);
+            var A = MatrixMarketReader.ReadStorage<double>(reader);
 
-                Assert.That(14, Is.EqualTo(A.RowCount));
-                Assert.That(14, Is.EqualTo(A.ColumnCount));
+            Assert.That(14, Is.EqualTo(A.RowCount));
+            Assert.That(14, Is.EqualTo(A.ColumnCount));
 
-                // Symmetric mtx file has 30 entries -> auto expand = 2 * 30 - 14 = 46.
-                Assert.That(46, Is.EqualTo(A.NonZerosCount));
-            }
+            // Symmetric mtx file has 30 entries -> auto expand = 2 * 30 - 14 = 46.
+            Assert.That(46, Is.EqualTo(A.NonZerosCount));
         }
 
         [Test]
         public void TestPatternSymmetric()
         {
-            var stream = ResourceLoader.GetStream("bcspwr01.mtx", "Double");
+            using var stream = ResourceLoader.GetStream("bcspwr01.mtx", "Double");
+            using var reader = new StreamReader(stream);
 
-            using (var reader = new StreamReader(stream))
-            {
-                var A = MatrixMarketReader.ReadStorage<double>(reader, false);
+            var A = MatrixMarketReader.ReadStorage<double>(reader, false);
 
-                Assert.That(39, Is.EqualTo(A.RowCount));
-                Assert.That(39, Is.EqualTo(A.ColumnCount));
+            Assert.That(39, Is.EqualTo(A.RowCount));
+            Assert.That(39, Is.EqualTo(A.ColumnCount));
 
-                // Symmetric mtx file has 85 entries, no auto expand.
-                Assert.That(85, Is.EqualTo(A.NonZerosCount));
-            }
+            // Symmetric mtx file has 85 entries, no auto expand.
+            Assert.That(85, Is.EqualTo(A.NonZerosCount));
         }
     }
 }
diff --git a/CSparse.Tests/IO/TestMatrixMarketWriter.cs b/CSparse.Tests/IO/TestMatrixMarketWriter.cs
index d10c984..e3584b2 100644
--- a/CSparse.Tests/IO/TestMatrixMarketWriter.cs
+++ b/CSparse.Tests/IO/TestMatrixMarketWriter.cs
@@ -8,12 +8,12 @@ namespace CSparse.Tests.IO
 
     public class TestMatrixMarketWriter
     {
-        private static readonly double[] DenseA = new[]
-        {
+        private static readonly double[] DenseA =
+        [
             1.0, 0.0, 0.5,
             0.0, 2.0, 0.1,
             0.5, 0.1, 3.0,
-        };
+        ];
 
         [Test]
         public void TestWriteSparse()
diff --git a/CSparse.Tests/Ordering/TestStronglyConnectedComponents.cs b/CSparse.Tests/Ordering/TestStronglyConnectedComponents.cs
index dda086c..2aaa7c7 100644
--- a/CSparse.Tests/Ordering/TestStronglyConnectedComponents.cs
+++ b/CSparse.Tests/Ordering/TestStronglyConnectedComponents.cs
@@ -25,8 +25,8 @@ public void TestScc()
             //
             // Adjacency matrix:
             
-            var A = SparseMatrix.OfRowMajor(8, 8, new double[8 * 8]
-            {
+            var A = SparseMatrix.OfRowMajor(8, 8,
+            [
                 1, 1, 0, 0, 0, 0, 0, 0,
                 0, 1, 1, 0, 1, 1, 0, 0,
                 0, 0, 1, 1, 0, 0, 1, 0,
@@ -35,7 +35,7 @@ public void TestScc()
                 0, 0, 0, 0, 0, 1, 1, 0,
                 0, 0, 0, 0, 0, 1, 1, 0,
                 0, 0, 0, 1, 0, 0, 1, 1
-            });
+            ]);
 
             int n = A.ColumnCount;
             
diff --git a/CSparse.Tests/ResourceLoader.cs b/CSparse.Tests/ResourceLoader.cs
index 5e2fa69..dd1df57 100644
--- a/CSparse.Tests/ResourceLoader.cs
+++ b/CSparse.Tests/ResourceLoader.cs
@@ -11,7 +11,7 @@ static class ResourceLoader
     {
         private const string NS = "CSparse.Tests.{Type}.Data";
 
-        private static Dictionary<string, object> cache = new Dictionary<string, object>();
+        private static readonly Dictionary<string, object> cache = [];
 
         public static Stream GetStream(string resource, string type)
         {
@@ -29,14 +29,13 @@ public static CompressedColumnStorage<T> Get<T>(string resource)
 
                 string path = NS.Replace("{Type}", type) + "." + resource;
 
-                object obj;
 
-                if (cache.TryGetValue(path, out obj))
+                if (cache.TryGetValue(path, out object obj))
                 {
                     return (CompressedColumnStorage<T>)obj;
                 }
 
-                var stream = Assembly.GetExecutingAssembly().GetManifestResourceStream(path);
+                using var stream = Assembly.GetExecutingAssembly().GetManifestResourceStream(path);
 
                 var matrix = MatrixMarketReader.ReadMatrix<T>(stream);
 
diff --git a/CSparse/CSparse.csproj b/CSparse/CSparse.csproj
index b5eb86b..52a920a 100644
--- a/CSparse/CSparse.csproj
+++ b/CSparse/CSparse.csproj
@@ -9,19 +9,23 @@
     <Description>CSparse.NET provides numerical methods for sparse LU, Cholesky and QR decomposition of real and complex linear systems.</Description>
     <Product>CSparse.NET</Product>
     <Company />
-    <Copyright>Copyright Christian Woltering © 2012-2025</Copyright>
+    <Copyright>Copyright Christian Woltering © 2012-2026</Copyright>
     <Authors>Christian Woltering</Authors>
-    <AssemblyVersion>4.3.0.0</AssemblyVersion>
-    <FileVersion>4.3.0.0</FileVersion>
-    <PackageTags>math sparse matrix lu cholesky qr decomposition factorization </PackageTags>
-    <Version>4.3.0</Version>
+    <AssemblyVersion>4.4.0.0</AssemblyVersion>
+    <FileVersion>4.4.0.0</FileVersion>
+    <PackageTags>math sparse matrix lu cholesky qr decomposition factorization</PackageTags>
+    <Version>4.4.0</Version>
     <AssemblyName>CSparse</AssemblyName>
     <RootNamespace>CSparse</RootNamespace>
     <PackageLicenseExpression>LGPL-2.1-only</PackageLicenseExpression>
     <PackageProjectUrl>https://github.com/wo80/CSparse.NET</PackageProjectUrl>
     <RepositoryUrl>https://github.com/wo80/CSparse.NET.git</RepositoryUrl>
     <RepositoryType>git</RepositoryType>
-    <PackageReleaseNotes>Version 4.3.0
+    <PackageReleaseNotes>Version 4.4.0
+
+* Add Refactorize methods to SparseCholesky, SparseLDL and SparseLU
+
+Version 4.3.0
 
 * Add net10.0 and remove net6.0 target framework.
 * Minor optimizations for matrix-vector multiplication.