Fitted parameters of the performed experiment with linear variations of ellipticity and/or position angle with radius (see Sect. 3.1). The two families of azimuthal variations, twist and ellipticity gradient, are displayed as green circles and red triangles, respectively. The results displayed with black squares are the ground-base case: the galaxy has isodensity contours that consist of ellipses displaying homoeidal symmetry (i.e., have the same axis ratio) and a single orientation. The open symbols characterize the results corresponding to the situation with a fixed fitted slope. The filled symbols display the median value of the final results after the constraint on the slope is relaxed. The error bars correspond to the 0.16 and 0.84 quantiles of the posterior distribution on the parameters. The x-axis tick labels indicate the type of variation considered: “base” refers to the ground-base case, “all” refers to variation occurring at all the radii, “in”, “middle”, and “out” indicate if the variation is limited to the region inside, around, or outside of the Einstein radius (see Sect. 2.2.2 for exact definitions). The y-axis quantities are defined in Table 1.