  We construct an on-line estimator with equidistant design for tracking a
smooth function from Stone-Ibragimov-Khasminskii class. This estimator has the
optimal convergence rate of risk to zero in sample size. The procedure for
setting coefficients of the estimator is controlled by a single parameter and
has a simple numerical solution. The off-line version of this estimator allows
to eliminate a boundary layer. Simulation results are given.
