manual: Add matrix->matrix-graph and matrix-graph->graph.

manual.scrbl

@@ -4,6 +4,7 @@
 	  	      require/typed require/typed/provide
 		      Any Boolean Void Sequenceof Listof List U False
 		      Mutable-HashTable Immutable-HashTable))
+  	  (for-label (only-in math/matrix Matrix))
 	  (for-label (only-in graph (matrix-graph? g:matrix-graph?)))
 	  (for-label typed/graph))
 
@@ -106,7 +107,14 @@ The opaque type corresponding to the predicate @racketlink[g:matrix-graph? "matr
 @defproc[(undirected-graph [edges (Listof (List Any Any))] [wgts (Listof Any) #f]) Graph]{}
 @defproc[(directed-graph [edges (Listof (List Any Any))] [wgts (Listof Any) #f]) Graph]{}
 
-@defproc[(matrix-graph? [g Graph]) Boolean]{}
+@defproc[(matrix->matrix-graph [mtx (Matrix Any)]) Matrix-Graph]{}
+@defproc[(matrix-graph->graph [g Matrix-Graph]) Graph]{
+
+An explicit conversion between @racket[Matrix-Graph] and @racket[Graph].
+This is necessary to use the general functions of the typed interface with
+matrix graphs.
+
+}
 
 @section{License}