The dependence of the test function on the phenomenological parameters used in the "NAV" ("New Algol Variable") algorithm (Andronov, 2012) is studied in the present work. Due to a presence of local minima, the method of minimisation contains two steps: the "brute force" minimisation at a grid in the 4D parameter space, and further iterations using the differential corrections. This method represents an effective approximation of the lightcurve using the special pattern (shape) for the primary and secondary minima separately. The application of the method to real star systems is briefly reviewed.
