MF relaxation of a non-force-free twisted magnetic flux tube. (a) Magnetic field lines of the flux tube in different colors at time 0. (b) Magnetic field lines starting from the same footpoints at time 900 of the ct run. (c) Degree of force-freeness as the weighted average of the sine of the angle between the magnetic field and the current density for the linde and ct run. (d) Degree of divergence-freeness as the average dimensionless divergence of the magnetic field for both runs.