function jdg(xc,yc,a,b,k)
% 画个椭园(一半虚线,一半实线)
% (xc,yc) is the position of center
% a is long radio
% b is short radio
% 画个椭园(一半虚线,一半实线)
% (xc,yc) is the position of center
% a is long radio
% b is short radio