NAME

       edge - Edge reference element

DESCRIPTION

       The edge reference element is K = [0,1].

             0---------1   x

       Curved  high  order Pk edges (k >= 1), in 2d or 3d geometries, are supported.  These edges
       have internal nodes, numbered as:

             0----2----1     0--2--3--1    0-2-3-4-1
                 P2              P3           P4

IMPLEMENTATION

       const size_t dimension = 1;
       const Float  measure = 1;
       const size_t n_vertex = 2;
       const point vertex [n_vertex] = {
               point(0),
               point(1) };