Add public methods to generate StronglyConnectedComponents and DulmageMendelsohn from SymbolicColumnStorage.

Author: wo80

CSparse/Ordering/DulmageMendelsohn.cs

@@ -105,14 +105,23 @@ public int Singletons
         /// <returns>Dulmage-Mendelsohn analysis</returns>
         public static DulmageMendelsohn Generate<T>(CompressedColumnStorage<T> matrix, int seed = 0)
              where T : struct, IEquatable<T>, IFormattable
+        {
+            return Generate(SymbolicColumnStorage.Create(matrix), seed);
+        }
+
+        /// <summary>
+        /// Compute coarse and then fine Dulmage-Mendelsohn decomposition. seed
+        /// optionally selects a randomized algorithm.
+        /// </summary>
+        /// <param name="A">The matrix represented by <see cref="SymbolicColumnStorage"/>.</param>
+        /// <param name="seed">0: natural, -1: reverse, random order otherwise</param>
+        /// <returns>Dulmage-Mendelsohn analysis</returns>
+        public static DulmageMendelsohn Generate(SymbolicColumnStorage A, int seed = 0)
         {
             int i, j, k, cnz, nc, nb1, nb2;
             int[] Cp, ps, rs;
             bool ok;
 
-            // We are not interested in the actual matrix values.
-            var A = SymbolicColumnStorage.Create(matrix);
-
             // Maximum matching
             int m = A.RowCount;
             int n = A.ColumnCount;
@@ -147,7 +156,7 @@ public static DulmageMendelsohn Generate<T>(CompressedColumnStorage<T> matrix, i
             // Fine decomposition
             int[] pinv = Permutation.Invert(p); // pinv=p'
 
-            var C = SymbolicColumnStorage.Create(matrix);
+            var C = A.Clone();
             A.Permute(pinv, q, C); // C=A(p,q) (it will hold A(R2,C2))
 
             Cp = C.ColumnPointers;

CSparse/Ordering/StronglyConnectedComponents.cs

@@ -48,19 +48,31 @@ private StronglyConnectedComponents(int m, int n)
         public static StronglyConnectedComponents Generate<T>(CompressedColumnStorage<T> matrix)
              where T : struct, IEquatable<T>, IFormattable
         {
-            return Generate(SymbolicColumnStorage.Create(matrix, false), matrix.ColumnCount);
+            return Generate(SymbolicColumnStorage.Create(matrix, false));
         }
-        
+
         /// <summary>
-        /// Find strongly connected components of A.
+        /// Compute strongly connected components of A.
         /// </summary>
-        /// <param name="A"></param>
-        /// <param name="n"></param>
-        /// <returns></returns>
-        internal static StronglyConnectedComponents Generate(SymbolicColumnStorage A, int n)
+        /// <param name="A">The matrix represented by <see cref="SymbolicColumnStorage"/>.</param>
+        /// <returns>Strongly connected components</returns>
+        public static StronglyConnectedComponents Generate(SymbolicColumnStorage A)
+        {
+            return Generate(A, A.ColumnCount);
+        }
+
+        /// <summary>
+        /// Compute strongly connected components of A.
+        /// </summary>
+        /// <param name="A">The matrix represented by <see cref="SymbolicColumnStorage"/>.</param>
+        /// <param name="size">The size of the matrix.</param>
+        /// <returns>Strongly connected components</returns>
+        public static StronglyConnectedComponents Generate(SymbolicColumnStorage A, int size)
         {
             // matrix A temporarily modified, then restored
 
+            int n = size;
+
             int i, k, b, nb = 0, top;
             int[] xi, p, r, Ap, ATp;