BiotSavart document format
General
This section describes the format used to save configuration
files.
This is also the format of the
clipboard contents if you copy objects there.
The format is plain text
comprising a list of object
descriptions. Each description begins on a new line with a word
giving the type of object, followed on the same line by an opening
brace. This brace marks the start of a multi-line character string
which continues until the matching brace. This character string
contains the defining commands for the object. The first command
is typically the command which sets the objects name. The layout
is as follows:
type {
name {the name}
...further commands...
}
The type should be one of the recognized object types
(Current, Loop, Solenoid, Revolved, Wire, Racetrack, Linear,
or Planar). If the software does not recognize the
type then the text between curly brackets which follows
it will simply be ignored. The commands which can be used within
the braces depend upon the type of the object, and are described
in the next section. The format of a command line is
command param
where command is a valid command word and param
is a parameter.
Length parameters can have units
(m, mm, cm, ft, in).
Vector position parameters can have units, but only after the entire vector.
String parameters are quoted by braces instead of quotes so
that strings can be nested. Multiline strings are possible --
once a string is opened with a left brace, it continues until
the matching right brace is found. For instance, the comment
command contains the contents of the Notes tab of the dialog
box:
comment {This text is the user's notes.
Note that in the file left and
right braces are prefaced by a backslash like this: \}
so that the nesting of strings is not messed up if the
user has left or right braces in the text.
}
Special characters in the file or clipboard contents:
| { |
opens a (possibly multi-line) string |
| } |
closes a string |
| \ |
escapes next character, e.g. \{ or \} are
not interpreted as string delimeters |
Commands
In the following n denotes an integer, x, y,
etc. are floating point numbers (possibly with units), v
a two or three-dimensional vector (possibly with units at the
end), and b is a Boolean value (0 or 1). Commands are not
case sensitive (i.e., positionx and positionX
are the same command).
Commands common to all objects
| name {the name} |
set object name |
| comment {notes...} |
the contents of the Notes tab |
| positionX x |
origin of object coordinate frame |
| positionY y |
|
| positionZ z |
|
| eulerPhi phi |
Euler angles (degrees) |
| eulerPsi psi |
|
| eulerTheta theta |
|
| visible b |
draw object? (b=0 suppresses drawing) |
Current object commands
Commands common to all conductors
| currentSupply {name} |
current supply name (no embedded blanks) |
| currentScale x |
current supply scale factor |
| winding x |
number of turns |
| wireDiameter x |
wire diameter |
| nPhi n |
steps used to draw a circle |
| phi phi0 phi1 |
drawing range (degrees) |
| fluxPathStep ds |
path stepsize for flux calculations (used by nonaxisymmetric conductors) |
| fluxPhiSteps n |
number of azimuthal steps for flux calculations (used by axisymmetric conductors) |
Loop object commands
Solenoid object commands
| innerRadius x |
inner radius of solenoid |
| outerRadius x |
outer radius of solenoid |
| length x |
full length of solenoid |
| resolution x |
used for calculation of loop spacing |
| paraxialR x |
near-axis threshold for cubic expansion |
| paraxialEnabled b |
enable near-axis approximations |
| drawLoops |
show loops used in calculation (2-D) |
Revolved object commands
| path {2-D path...} |
See below for 2-D path commands |
| drawElements |
show elements (calculation loops) used in calculation |
| reverse |
reverse polygon defined by path} |
2-D path commands (used by Revolved object)
| resolution x |
loop spacing for later segements |
| start v |
set starting position to v |
| goto v |
make segment to position v |
| center v |
center for turn |
| dtheta theta |
used if resolution is zero |
| turn theta |
turn through theta degrees |
| close |
close polygon |
Wire object commands
3-D path commands (used by Wire and Linear
objects)
| resolution x |
marker spacing for later segments |
| start v |
starting position (object coordinates) |
| goto v |
line segment to new position |
| axis v1 v2 |
define axis for rotations |
| center v |
define center |
| normal v |
define normal |
| pitch x |
pitch, in advance/revolution |
| dtheta theta |
stepsize for turns, degrees |
| turn theta |
turn through angle theta, degrees |
| turn x t |
turn through x turns |
| close |
close wire (optional) |
Racetrack object commands
| length x |
length of straight section |
| span x |
distance between straights |
| width x |
width width of conductor (in plane) |
| height x |
height (out of plane) |
| resolution x |
controls subdivision into wires |
| nturn n |
number of segments in end turn |
Linear object commands
| path {3-D path...} |
See 3-D Path section |
| xRange x1 x2 |
set plotting range x1 < x < x2 meters |
| yRange B1 B2 |
set plotting range B1 < B < B2 tesla |
| plot yvars vs xvar |
yvars is one or more of bx, by,
bz, or b |
|
xvar is one of x, y, z,
or s |
| macro {macro sequence...} |
See macro section |
Planar object commands
| grid nU nV |
grid mesh is nU by nV |
| uX x |
x-component of u |
| uY y |
...etc. |
| uZ z |
|
| vX x |
|
| vY y |
|
| vZ z |
|
| plotrange B1 B2 |
set plotting range B1 < B < B2 tesla |
| contour x |
set contour spacing to x tesla |
| apartWindow b |
plot in separate window? |
| drawContour b |
draw contour on configuration window? |
| drawGrid b |
draw grid on configuration window? |
| drawFrame b |
draw frame on configuration window? |
The Loop and Current objects are examples of objects which
include a table as part of their definitions. To represent a table
we use nested strings. For example, to have two loops, one of
2cm radius at z=1cm carrying 0.3A and one with opposite current
of 3cm radius at z=-5mm, we have
Loop {
name {Two loop object}
currentSupply mySupply
loops {
{ {2cm} {1cm} {1} }
{ {3cm} {-5mm} {-1} }
}
}
Current {
supplies {
{ {mySupply} {0.3} }
}
}
The argument of the loops command is a string consists
of a set of substrings, one string for each loop. Each of these
strings consists, in turn, of three strings, specifying the radius,
the alitude, and the number of turns in each loop. This is the
general format of a table in BiotSavart files: the table is a
string consisting of substrngs which are the rows of the table,
each row made up of substrings which are the table entries.
For objects with a path description, e.g., the path of a Wire
through space, the path commands are in the string which is the
argument of the path command:
Wire {
name {a short wire}
path {
start 0 0 0
goto 1 0 1 cm
}
}