Update GetHashCode() method of CompressedColumnStorage class.

Author: wo80

CSparse/CSparse.csproj

@@ -19,14 +19,15 @@
     <RootNamespace>CSparse</RootNamespace>
     <PackageLicenseExpression>LGPL-2.1-only</PackageLicenseExpression>
     <PackageProjectUrl>https://github.com/wo80/CSparse.NET</PackageProjectUrl>
-    <RepositoryUrl>https://github.com/wo80/CSparse.NET</RepositoryUrl>
+    <RepositoryUrl>https://github.com/wo80/CSparse.NET.git</RepositoryUrl>
     <RepositoryType>git</RepositoryType>
     <PackageReleaseNotes>
 		The major version change is due to the removal of obsolete methods in the Converter class. Visibility of that class was changed from public to internal. In case those obsolete methods were still used, please switch to the static conversion methods provided by the SparseMatrix class.
 
 		Other changes in version 4.0.0:
 
 		* Addition of helper method Helper.ValidateStorage(...) to validate the structure of a sparse matrix.
+		* Update to GetHashCode() method of CompressedColumnStorage class.
 		* Improvements to documentation.
 	</PackageReleaseNotes>
   </PropertyGroup>

CSparse/Storage/CompressedColumnStorage.cs

@@ -471,7 +471,7 @@ public abstract void Add(T alpha, T beta, CompressedColumnStorage<T> other,
             CompressedColumnStorage<T> result);
 
         /// <summary>
-        /// Sparse matrix multiplication, C = A*B
+        /// Sparse matrix multiplication, C = A * B, where A is the current instance.
         /// </summary>
         /// <param name="other">The sparse matrix multiplied to this instance (from the right).</param>
         /// <returns>C = A*B</returns>
@@ -896,26 +896,20 @@ internal bool Resize(int size)
         /// Serves as a hash function for a particular type.
         /// </summary>
         /// <returns>
-        /// A hash code for the current <see cref="T:System.Object"/>.
+        /// A hash code for the current <see cref="CompressedColumnStorage{T}"/>.
         /// </returns>
         public override int GetHashCode()
         {
-            var hashNum = Math.Min(this.NonZerosCount, 25);
+            var hashNum = Math.Min(NonZerosCount, 50);
             int hash = 17;
-            int i, p, k = 0;
             unchecked
             {
-                for (i = 0; i < columns; i++)
-                {
-                    for (p = ColumnPointers[i]; p < ColumnPointers[i + 1]; p++)
-                    {
-                        hash = hash * 31 + Values[p].GetHashCode();
+                hash = hash * 31 + NonZerosCount;
 
-                        if (++k > hashNum)
-                        {
-                            return hash;
-                        }
-                    }
+                for (int i = 0; i < hashNum; i++)
+                {
+                    hash = hash * 31 + RowIndices[i];
+                    hash = hash * 31 + Values[i].GetHashCode();
                 }
             }
             return hash;