plot of optics evolution along a single element

[simoneliuzzo]

Dear @lfarv and @swhite2401 ,

when asking to atplot to produce optics in transferline mode, the case of a lattice composed of a single element seems not an option for atplot. Below an example:

optics_struct.beta = [2,1];
optics_struct.alpha = [0,0];
optics_struct.mu = [0,0];
optics_struct.ClosedOrbit = [0,0,0,0];
optics_struct.Dispersion = [0,0,0,0]';

% FAILS
%figure; atplot({atdrift('D',1)}, 'twiss_in', optics_struct);

% WORKS
figure; atplot({atdrift('D',1);atdrift('D',1)}, 'twiss_in', optics_struct);

Since I noticed this only now, I posted this message. May be it is expected.

thank you
best regards
Simone

[lfarv]

This is fixed in #854.