Test of the MV1 method with FRs expanding with a typically observed rate (ζ = 1). The simulated data are defined within the time interval where B_z, FR ≥ 0. Panel a shows the results for a circular FR and panel b for an elliptical one. The FR axis is oriented with i = 90° and λ = 0° so that the simulated observed and FR frames are the same (Fig. 1). Left column: θ_x, θ_y, θ_z are the angles in degrees between the x, y, z directions, respectively, of the FR and MV frames. Middle left column: Δi and Δλ quantify the difference of axis orientations between the FR and the one found by MV, so the orientation biases. Middle right column: ratios of the eigenvalues eν_min, eν_int and eν_max. Right column: ratio of the maximum values of B_z, MV to B_z, FR (amplified by a factor of 100 for the first ratio). The horizontal dotted lines and the yellow regions are landmarks to compare the graphs.