Example of how an adjustment to the bottom point (r_b, F(r_b)) when constructing the F(r) affects the resulting f(r). The flow model used in the example is MC1 whose bottom is at r_b = 0.7R_⊙. Left panel: assigned points (filled circles) for constructing the F(r) of model MC1 connected by cubic spline interpolation (red curve). The value of F(r_b) for model MC1 is deliberately increased (MC1⁺, blue curve) or decreased (MC1⁻, green curve) by one. Right panel: resulting f(r) from the three F(r) in the left panel by computing Eq. (A.1). The values of f(r_t) for MC1⁺ and MC1⁻ are 25360.8 and −25360.8, respectively.