twiss_output

• type: action/setup command.
• function: compute and output Twiss parameters, or set up to do so.

&twiss_output
    STRING filename = NULL;
    long matched = 1;
    long output_at_each_step = 0;
    long output_before_tune_correction = 0;
    long final_values_only = 0;
    long statistics = 0;
    long radiation_integrals = 0;
    long concat_order = 3;
    double beta_x = 1;
    double alpha_x = 0;
    double eta_x = 0;
    double etap_x = 0;
    double beta_y = 1;
    double alpha_y = 0;
    double eta_y = 0;
    double etap_y = 0;
    STRING reference_file = NULL;
    STRING reference_element = NULL;
    long reference_element_occurrence = 0;
&end

• filename -- The (incomplete) name of an SDDS file to which the Twiss parameters will be written. Recommended value: ``%s.twi''.
• matched -- A flag indicating, if set, that the periodic or matched Twiss parameters should be found.
• output_at_each_step -- A flag indicating, if set, that output is desired at each step of the simulation.
• output_before_tune_correction -- A flag indicating, if set, that output is desired both before and after tune correction.
• final_values_only -- A flag indicating, if set, that only the final values of the Twiss parameters should be output, and not the parameters as a function of s.
• statistics -- A flag indicating, if set, that minimum, maximum, and average values of Twiss parameters should be computed and included in output.
• radiation_integrals -- A flag indicating, if set, that radiation integrals should be computed and included in output.
• beta_X, alpha_X, eta_X, etap_X -- If matched is zero, the initial values for the X plane.
• concat_order -- Order of matrix concatenation to use for determining matrix for computation of Twiss parameters. Using a lower order will result in inaccuracy for nonlinear lattices with orbits. However, if the orbit is zero, it is much faster to use concat_order=1.
• reference_file -- If given, the name of a file from which twiss parameter data will be taken to give the starting values. Ignored if matched is nonzero. The file should have the beta and alpha functions with the same names as the file created by this command.
• reference_element -- Element in reference_file at which to take the twiss parameter values. If not given, the values at the last element in reference_file are used.
• reference_element_occurrence -- Ignored if reference_element is not given. Otherwise, the occurence number of reference_element to use. If 0, the last occurence is used.