INTERFACE ModKamSpring;

IMPORT Energy;

TYPE
  T <: Public;
  Public = Energy.T OBJECT
    length : REAL;   (* desirable length of a single edge in the display
                        plane *)
    strength : REAL; (* a constant *)
    METHODS
      init(): T;
    END;
  (*
    Kamada's version has a spring between every pair of vertices
    u,v adjacents or not; whose length is equal to the graph-theoretical
    distance between u and v in T. 
  *)
  
END ModKamSpring.