Cosmetics.

[mtp.git] / mtp_graph.h

diff --git a/mtp_graph.h b/mtp_graph.h
index 9093a8b..9f50ae4 100644 (file)
--- a/mtp_graph.h
+++ b/mtp_graph.h
@@ -37,18 +37,35 @@ class Vertex;
 class Edge;
 
 class MTPGraph {
+  // Set the distance_from_source fields to the number of DP
+  // iterations needed to update it. Abort if the graph is not a DAG.
+  int compute_dp_ranks();
+
+  // Uses the estimated vertex distances to the source to make all the
+  // edge lengths positive, resulting in an identical added value to
+  // all the paths from the same initial node to the same final node
+  // (in particular from source to sink)
   void update_positivized_lengths();
+
+  // It may happen that numerical errors in update_positivized_lengths
+  // make the resulting lengths negative, albeit very small. The
+  // following method forces all negative lengths to zero, and prints
+  // the total correction when compiled in VERBOSE mode.
   void force_positivized_lengths();
-  // Set the edge pred_edge_toward_source correspondingly to the path
-  // of shortest length. The current implementation is not Dijkstra's!
+
+  // Visit the vertices according to _dp_order and update their
+  // distance from the source
+  void dp_compute_distances();
+
+  // Set in every vertex pred_edge_toward_source correspondingly to
+  // the path of shortest length. The current implementation is
+  // Dijkstra with a Binary Heap (and not with Fibonnaci heap (yet))
   void find_shortest_path();
-  // Follows the path starting on edge e and returns its length. If
-  // nodes is non-null, stores in it the nodes met along the path.
-  int retrieve_one_path(Edge *e, Path *path);
-  // Returns if the graph is a DAG
-  int is_dag();
 
-  Vertex **_front, **_new_front;
+  // Follows the path starting on edge e and returns the number of
+  // nodes to reach the sink. If path is non-null, stores in it the
+  // nodes met along the path, and computes path->length properly.
+  int retrieve_one_path(Edge *e, Path *path);
 
   int _nb_vertices, _nb_edges;
   Vertex *_source, *_sink;
@@ -56,6 +73,14 @@ class MTPGraph {
   Edge *_edges;
   Vertex *_vertices;
 
+  // For Dijkstra
+  Vertex **_heap;
+  int _heap_size;
+
+  // Updating the distances from the source in that order will work in
+  // the original graph (which has to be a DAG)
+  Vertex **_dp_order;
+
 public:
 
   // These variables are filled when retrieve_disjoint_paths is called
@@ -67,7 +92,12 @@ public:
 
   ~MTPGraph();
 
+  // Compute the family of paths with minimum total length, set the
+  // edge occupied fields accordingly.
   void find_best_paths(scalar_t *lengths);
+
+  // Retrieve the paths corresponding to the occupied edges, and save
+  // the result in the nb_paths and paths fields.
   void retrieve_disjoint_paths();
 
   void print(ostream *os);