Adapt example

examples/symm_twiss_and_match/000_symm_twiss_and_match.py

@@ -18,6 +18,12 @@
 )
 half_cell.particle_ref = xt.Particles(p0c=2e9)
 
+# Add observation points every 1 m (to see betas inside bends)
+half_cell.discard_tracker()
+s_cut = np.arange(0, half_cell.get_length(), 1.)
+half_cell.cut_at_s(s_cut)
+
+# Attach knobs to quadrupoles
 half_cell.vars['kqf'] = 0.027/2
 half_cell.vars['kqd'] = -0.0271/2
 half_cell.element_refs['qf1'].k1 = half_cell.vars['kqf']
@@ -32,17 +38,11 @@
     vary=xt.VaryList(['kqf', 'kqd'], step=1e-5),
 )
 
-
-# Add observation points every 1 m
-half_cell.discard_tracker()
-s_cut = np.arange(0, half_cell.get_length(), 1.)
-half_cell.cut_at_s(s_cut)
-
 # Twiss with periodic symmetric boundary
 tw_half_cell = half_cell.twiss4d(init='periodic_symmetric')
 
+# Plot
 import matplotlib.pyplot as plt
 plt.close('all')
 tw_half_cell.plot()
-
 plt.show()