  The paper deals with a well-known extremum seeking scheme by proving
uniformity properties with respect to the amplitudes of the dither signal and
of the cost function. Those properties are then used to show that the scheme
guarantees the global minimiser to be semi-global practically stable despite
the presence of local saddle points. To achieve these results, we analyse the
average system associated with the extremum seeking scheme via arguments based
on the Fourier series.
