.\"
.de Id
..
.de Sp
.if n .sp
.if t .sp 0.4
..
.TH quadrangle 7rheolef "rheolef-7.0" "rheolef-7.0" "rheolef-7.0"
.\" label: /*Class:quadrangle
.SH NAME
\fBquadrangle\fP - Quadrangular reference element
.\" skip: @cindex quadrangle
.\" skip: @cindex reference element
.SH DESCRIPTION

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

.\" begin_example
.Sp
.nf
      y
.PP
      3---------2
      |         |
      |         |
      |         |
      |         |
      0---------1   x
.Sp
.fi
.\" end_example
Curved high order Pk quadrangles (k >= 1), in 2d or 3d geometries, are supported.
These quadrangles have additional edge-nodes and face-nodes.
.SH 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.
.\" begin_example
.Sp
.nf
      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
.Sp
.fi
.\" end_example
.\" END
.SH IMPLEMENTATION
.\" begin_example
.Sp
.nf
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 } };
.Sp
.fi
.\" end_example
.SH COPYRIGHT
Copyright (C) 2000-2018 Pierre Saramito <Pierre.Saramito@imag.fr> GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>.
This is free software: you are free to change and redistribute it.  There is NO WARRANTY, to the extent permitted by law.