DESCRIPTION

The quadrangular reference element is [-1,1]^2.

NUMBERING

      y
      3---------2
      |         |
      |         |
      |         |
      |         |
      0---------1   x

Curved high order Pk quadrangles (k >= 1), in 2d or 3d geometries, are supported. These quadrangles have additional edge-nodes and face-nodes.

THESE NODES ARE NUMBERED AS

 first vertex, then edge-node, following the edge numbering order and orientation, and finally the face internal nodes, following the quadrangle lattice. See below for edge numbering and orientation.

      3-----6-----2   3---9---8---2
      |           |   |           |
      |           |  10  14  15   7
      7     8     5   |           |
      |           |  11  12  13   6
      |           |   |           |
      0-----4-----1   0---4---5---1
            P2              P3

IMPLEMENTATION

const size_t dimension = 2;
const Float  measure = 4;
const size_t n_vertex = 4;
const point vertex [n_vertex] = {
        point(-1,-1),
        point( 1,-1),
        point( 1, 1),
        point(-1, 1) };
const size_t  n_edge = 4;
const size_t edge [n_edge][2] = {
        { 0, 1 },
        { 1, 2 },
        { 2, 3 },
        { 3, 0 } };