Hi (Pavel), I have a dataset (P31) which I am processing with the pairwise combinations of reindexing operators (4 incl. no reindexing therefore h,k,l) and twin laws (4 incl. no twinning as h,k,l). While some of these combinations are fine during refinement (Vers 1.11.1), for some combinations I get the following error, which ultimately kills the refinement. Thanks in advance and apologies if I am missing something stupid. Incidentally, a different dataset seems to tolerate all combinations. *approx_equal eps: 1e-05* *approx_equal multiplier: 10000000000.0* *0.512707954357 approx_equal ERROR* *0.514972857238 approx_equal ERROR* Traceback (most recent call last): File "/Applications/phenix-1.11.1-2575/build/../modules/phenix/ phenix/command_line/refine.py", line 11, in <module> command_line.run(command_name="phenix.refine", args=sys.argv[1:]) File "/Applications/phenix-1.11.1-2575/modules/phenix/phenix/refinement/command_line.py", line 154, in run call_back_handler=call_back_handler) File "/Applications/phenix-1.11.1-2575/modules/phenix/phenix/refinement/driver.py", line 1529, in run call_back_handler = call_back_handler).result File "/Applications/phenix-1.11.1-2575/modules/phenix/phenix/refinement/strategies.py", line 121, in __init__ log = log) File "/Applications/phenix-1.11.1-2575/modules/phenix/phenix/refinement/fmodels.py", line 159, in run fmodel.update_solvent_and_scale(initialise=True) File "/Applications/phenix-1.11.1-2575/modules/cctbx_project/ mmtbx/twinning/twin_f_model.py", line 797, in update_solvent_and_scale params=params, log=log, apply_back_trace=apply_back_trace) File "/Applications/phenix-1.11.1-2575/modules/cctbx_project/mmtbx/f_model/f_model.py", line 1457, in update_all_scales params = params, log = log, refine_hd_scattering=refine_hd_scattering) File "/Applications/phenix-1.11.1-2575/modules/cctbx_project/ mmtbx/bulk_solvent/f_model_all_scales.py", line 38, in __init__ refine_hd_scattering = refine_hd_scattering, log = log) File "/Applications/phenix-1.11.1-2575/modules/cctbx_project/ mmtbx/bulk_solvent/f_model_all_scales.py", line 61, in compute refine_hd_scattering = refine_hd_scattering) File "/Applications/phenix-1.11.1-2575/modules/cctbx_project/ mmtbx/bulk_solvent/f_model_all_scales.py", line 329, in update_solvent_and_scale_twin * assert approx_equal(self.r_all(), o_kbu_sol.r(), 1.e-5)* *AssertionError*