Input File Format
The input file is a text file. It has been designed to balance
ease of data entry with simplicity of programming. Data can be
entered in an arbitrary order but it makes sense to define the
mesh size first so that range checking can be performed on any
coordinates. Lines starting with an exclamation mark ('!') can be
used to place comments. Start of data is indicated by an
identifier, the first character of which is a colon (':').
In the following descriptions, the vertical bar is used to
indicate a line break and curly brackets are used to enclose
items which should be repeated as often as necessary.
- :MESH_SIZE | nx ny nz |
- The number of nodes in each direction. The maximum values
are displayed when the program is run. If omitted, a mesh
of the maximum size will be used.
- :DL | node_spacing |
- The node spacing in metres. Strictly speaking, the node
spacing is not required since it is only used to scale
the electric and magnetic fields. However, it has been
included so that the timestep can be calculated, if
required.
- :TIMESTEPS | number_of_timesteps |
- The number of timesteps to be performed (must be
specified).
- :OUTPUT_FILE | filename |
- The name of the output file. If omitted, the filename
must be entered interactively.
- :BOUNDARIES | number | { reflection_coefficient type
x1 y1 z1 x2 y2 z2 | }
- Boundary conditions of arbitrary reflection coefficient.
The type consists of two characters: the first
specifies the direction parallel to the link-line (X, Y
or Z) and the second gives the orientation. For
boundaries on the edge of the mesh, the orientation is
'N' for a boundary on the negative side of the node
(taking the centre as the origin) or 'P' for a boundary
on the positive side. For internal boundaries, the
orientation is set to '0' and the reflection coefficient
is applied to pulses incident from both sides of the
boundary. In this case, the coordinates must refer to the
lowest numbered node to which the link-line is conected,
in the direction parallel to the link-line. The two sets
of coordinates must define the extent of a plane normal
to the link-lines. Boundaries must be placed to terminate
all of the transmission-lines on the edge of the mesh.
- :EXCITE | number | { field amplitude x1 y1 z1 x2 y2
z2 }
- Impulse excitation. The field may be one of EX, EY, EZ,
HX, HY or HZ. The two sets of coordinates may, in
general, define a cuboid region of nodes.
- :OUTPUT | number | { field x y z }
- Output points. The field can take the same values as for
excitation.
- :END
- This should be placed at the bottom of the file to
indicate that there is no more data.