function circles(a0,b0,radius,n)
%
%
% displaying a circle.
%

delata_radius=radius/n;
radius_local=0;
for j=1:n
    % radius_local=radius_local+delata_radius;
    % radius_local=radius/j;
    radius_local=j*delata_radius;
    circle(a0,b0,radius_local);
end % j