&find_aperture
STRING output = NULL;
STRING search_output = NULL;
STRING boundary = NULL;
STRING mode = "many-particle";
double xmin = -0.1;
double xmax = 0.1;
double ymin = 0.0;
double ymax = 0.1;
long nx = 21;
long ny = 11;
long n_splits = 0;
double split_fraction = 0.5;
double desired_resolution = 0.01;
long assume_nonincreasing = 0;
long verbosity = 0;
long offset_by_orbit = 0;
&end
output -- The (incomplete) name of an SDDS file to send output to.
Recommended value: ``%s.aper''.
mode -- May be ``many-particle'', ``single-particle'',
``one-line'', ``three-line'', ``five-line'', ``seven-line'',
``nine-line'', or ``eleven-line''. Many-particle searching is much
faster than single-particle, but does not allow interval splitting to
search for the aperture boundary. Both ``many-particle'' and
``single-particle'' modes involve searching from the outside inward,
which improves speed but may result in including islands.
The n-line modes avoid this by searching form the origin
outward. Of these, the one-line and three-line modes are special:
one-line mode searches the line from the origin to
. three-line mode searches this line, plus the lines from
the origin to 
and 
. For 
-line modes
with 
, lines are explored from 
to
, where 
takes
values from 
to 
. In these modes, the output file contains
a parameter called ``Area,'' which gives the area of the dynamic aperture.
search_output -- The (incomplete) name of an SDDS file for output of detailed
information on each tracked particle (single-particle mode only). Recommended value:
``%s.apso''.
boundary -- The (incomplete) name of an SDDS
file for the boundary points of the aperture search. Recommended value: ``%s.bnd''.
Valid for many- and single-particle modes.
xmin, xmax, ymin, ymax -- Region of the aperture search.
The minimum values are relevant only for many- and single-particle modes.
nx -- For many- and single-particle modes, the number of x values to take in initial search.
For line modes, this determines the initial x and y step sizes via
and
.
ny -- For many- and single-particle modes, the number of y values to take in search.
Ignored for line modes.
n_splits -- If positive, the number of times to do
interval splitting. Interval splitting refers to searching between
the original grid points in order to refine the results. This is done
only for single-particle and line modes.
split_fraction -- If interval splitting is done, how the interval is split.
desired_resolution -- If interval splitting is done,
fraction of xmax-xmin to which to resolve the aperture. Ignored for all but single-particle
mode.
assume_nonincreasing -- If this variable is non-zero, the search assumes that the aperture
at
is no larger than that at 
. This results in tracking of
fewer particles but may give a pessimistic result. Used only for single- and multi-particle
modes.
offset_by_orbit -- A flag indicating whether to offset
the transverse beam coordinates by the closed orbit before tracking. The default value is
zero for backward compatibility, but the recommended value is 1.
verbosity -- A larger value results in more printouts during computations.