Special Shapes for Optimal Phenomenological Approximations of Astronomical Signals

We discuss different methods for phenomenological approximations of signals with (generally) irregularly spaced arguments. Such signals may be classified as periodic, multi-periodic, quasi-periodic (cyclic), burst-type and flicker-type (see e.g. a review by Andronov (2003)). In this talk, we concentrate on (nearly) periodic light curves of the Algol-type eclipsing variables. Having no possibility to determine all physical parameters for all stars and to make physical modeling, the phenomenological fits are used. This is especially important for discovery papers, when there are often available only mono-chromatic photometric data, without estimates of temperature and orbital velocities of the components.