- type: major action command.
- function: compute chaos map from tracking. Note that the number of turns tracked is set by the run_control command.
- can use parallel resources (Pelegant)
- Command syntax, including use of equations and subcommands, is discussed in 7.2.
- NB: this feature is new in 2019.4 and somewhat experimental. Please report problems on the forum.

&chaos_map

STRING output = NULL;

double xmin = -0.1;

double xmax = 0.1;

double ymin = 1e-6;

double ymax = 0.1;

double delta_min = 0;

double delta_max = 0;

long nx = 20;

long ny = 21;

long ndelta = 1;

long forward_backward = 0;

double change_x = 1e-6;

double change_y = 1e-6;

long verbosity = 1;

&end

STRING output = NULL;

double xmin = -0.1;

double xmax = 0.1;

double ymin = 1e-6;

double ymax = 0.1;

double delta_min = 0;

double delta_max = 0;

long nx = 20;

long ny = 21;

long ndelta = 1;

long forward_backward = 0;

double change_x = 1e-6;

double change_y = 1e-6;

long verbosity = 1;

&end

- output — The (incomplete) name of an SDDS file to send output to. Recommended value: “%s.cmap”. For the parallel version, particles will be listed in essentially random order. If needed, sddssort can be used to sort particles by initial coordinates.
- xmin, xmax — Limits of grid of initial x coordinates for tracking.
- ymin, ymax — Limits of grid of initial y coordinates for tracking. ymin should be a small, positive value so that there is some betatron oscillation from which to get the tune.
- delta_min, delta_max — Limits of grid of initial δ coordinates for tracking. Note that particles are not centered around the dispersive closed orbit. Hence, the tracking is appropriate to simulation of dynamics from a touschek scattering event.
- nx — Number of values of x coordinate in the grid.
- ny — Number of values of y coordinate in the grid.
- ndelta — Number of values of δ coordinate in the grid.
- forward_backward — If non-zero, uses the forward/backward integration technique of Y. Li
et al. [56]. The number of passes tracked is still controlled by the n_passes parameter of
run_control. In addition, the number of iterations of forward and backward tracking is given
by the value of forward_backward. If zero, a less interesting technique is used that computes
the change in J
_{x}and J_{y}from tracking with small changes in initial conditions. - change_x, change_y — If forward_backward is zero, gives the perturbation to initial x and y used to assess chaotic motion from divergence of trajectories.
- verbosity — If nonzero, prints possibly useful information while running.

chromaticity