Hi, I went into a problem related to the 'chi2' symbol being undefined in the C module for relaxation dispersion. This is not very surprising since the 'math_fns/c_chi2.*' code is not compiled with the 'math_fns/relax_disp.*' and 'math_fns/dispersion.*' codes, as it is also used for the 'math_fns/relax_fit.*' and 'math_fns/exponential.*' codes... I am not sure how to handle this to avoid duplicating the 'math_fns/c_chi2.*' code... Should I put all C modules together and compile them as one, that is modifying 'sconstruct.relax_fit()' to compile all C modules : 'c_chi2', 'exponential', 'dispersion', 'relax_fit' and 'relax_disp', and rename the function something like 'sconstruct.relax_curves(), or anything else more general ? Or am I completely wrong ??? Thanks ! Séb :) ==================== The actual error... ==================== ./relax Traceback (most recent call last): File "./relax", line 53, in <module> from prompt import interpreter File "/home/semor/pse-4/collaborations/relax/relax-1.3--relax_disp_3/prompt/interpreter.py", line 50, in <module> from dx import OpenDX File "/home/semor/pse-4/collaborations/relax/relax-1.3--relax_disp_3/prompt/dx.py", line 35, in <module> import opendx.main File "/home/semor/pse-4/collaborations/relax/relax-1.3--relax_disp_3/opendx/main.py", line 32, in <module> import isosurface_3D File "/home/semor/pse-4/collaborations/relax/relax-1.3--relax_disp_3/opendx/isosurface_3D.py", line 31, in <module> from base_map import Base_Map File "/home/semor/pse-4/collaborations/relax/relax-1.3--relax_disp_3/opendx/base_map.py", line 36, in <module> from specific_fns.setup import get_specific_fn File "/home/semor/pse-4/collaborations/relax/relax-1.3--relax_disp_3/specific_fns/setup.py", line 30, in <module> from specific_fns.relax_disp import Relax_disp File "/home/semor/pse-4/collaborations/relax/relax-1.3--relax_disp_3/specific_fns/relax_disp.py", line 42, in <module> from maths_fns.relax_disp import setup, func, dfunc, d2func, back_calc_I ImportError: /home/semor/pse-4/collaborations/relax/relax-1.3--relax_disp_3/maths_fns/relax_disp.so: undefined symbol: chi2