1# Example macro triangulation for a mesh with periodic boundaries: a
2# topological torus.
3
4DIM: 2
5DIM_OF_WORLD: 2
6
7number of elements: 8
8number of vertices: 9
9
10element vertices:
11 4 0 1
12 2 4 1
13 4 2 5
14 8 4 5
15 4 8 7
16 6 4 7
17 4 6 3
18 0 4 3
19
20vertex coordinates:
21 -1.0 -1.0
22  0.0 -1.0
23  1.0 -1.0
24 -1.0  0.0
25  0.0  0.0
26  1.0  0.0
27 -1.0  1.0
28  0.0  1.0
29  1.0  1.0
30
31# Neighbours need not be specified, but if so, then the neighbourhood
32# information should treat periodic faces as interior faces. We leave
33# the neighbourhood information commented out such that it can be
34# determined by the geometric face transformations.
35
36# example for a torus:
37# element neighbours:
38#   5  1  7
39#   0  4  2
40#   7  3  1
41#   2  6  4
42#   1  5  3
43#   4  0  6
44#   3  7  5
45#   6  2  0
46
47# In principle it is possible to specify boundary types for periodic
48# faces; those are ignored during "normal" operation, but can be
49# accessed by using the special fill-flag FILL_NON_PERIODIC during
50# mesh-traversal. This is primarily meant for defining parametric
51# periodic meshes: the finite element function defining the mesh
52# geometry is -- of course -- not periodic.
53
54element boundaries:
55 2 0 0
56 0 2 0
57 1 0 0
58 0 1 0
59 2 0 0
60 0 2 0
61 1 0 0
62 0 1 0
63
64# Geometric face transformations. It is also possible to specify those
65# in the application program.
66#
67number of wall transformations: 2
68
69wall transformations:
70# generator #1
71 1 0 2
72 0 1 0
73 0 0 1
74# generator #2
75 1 0 0
76 0 1 2
77 0 0 1
78
79# For each face of each element of the triangulation the number of the
80# face transformation attached to it. Counting starts at 1, negative
81# numbers mean the inverse. Expected is the face transformation which
82# maps the macro triangulation to its neighbour across the respective
83# face. It is possible to omit this section in which case the
84# per-element face transformations are computed.
85#
86#element wall transformations:
87# -2  0  0
88#  0 -2  0
89#  1  0  0
90#  0  1  0
91#  2  0  0
92#  0  2  0
93# -1  0  0
94#  0 -1  0
95
96# Combinatorical face transformations. These, too, can be omitted.
97#
98# You will observe that there are "duplicate lines" below. Indeed, but
99# this does not matter: you really have to group the vertex-mappings
100# in pairs, the first two lines mean:
101#
102# "map the face defined by vertex 0 and 1 to the face defined by
103# vertex 6 and 7, in that orientation".
104#
105#number of wall vertex transformations: 4
106
107#wall vertex transformations:
108# 0 6
109# 1 7
110
111# 1 7
112# 2 8
113
114# 0 2
115# 3 5
116
117# 3 5
118# 6 8
119
120# (X)Emacs stuff (for editing purposes)
121# Local Variables: ***
122# comment-start: "# " ***
123# End: ***
124