---
name: "quadrangle"
section: "7rheolef"
platform: "linux"
package: "librheolef-dev"
version: "7.0-2+b1"
release: "Debian 10 (Buster)"
platforms: ["linux"]
url: "https://new.carta.tech/quadrangle/7rheolef"
---

# quadrangle(7rheolef)

Quadrangular reference element

## NAME

**quadrangle** - Quadrangular reference element

## 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 } };

```

## 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.