find_aperture

• type: action command.
• function: find the aperture in (x, y) space for an accelerator.

&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 verbosity = 0;    
    long assume_nonincreasing = 0;
&end

• output -- The (incomplete) name of an SDDS file to send output to. Recommended value: ``%s.aper''.
• 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''.
• xmin, xmax, ymin, ymax -- Region of the aperture search.
• mode -- May be ``many-particle'' or ``single-particle''. Many-particle searching is much faster, but does not allow interval splitting to search for the aperture boundary.
• nx -- Number of x values to take in initial search.
• ny -- Number of y values to take in search.
• 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.
• 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.
• assume_nonincreasing -- If this variable is non-zero, the search assumes that the aperture at ${\rm y+sign(y)*\Delta y}$ is no larger than that at ${\rm y}$. This results in tracking of fewer particles but may give a pessimistic result.
• verbosity -- A larger value results in more printouts during computations.