for p=1:Nt
thp=(p-1)2pi/Nt;
thp1=thp-pi/Nt;
thp2=thp+pi/Nt;
x=[rcos(thp1),1.9rcos(thp),rcos(thp2),r*cos(thp1)];
y=[rsin(thp1),1.9rsin(thp),rsin(thp2),r*sin(thp1)];
fill(x,y,[1,1,1]);hold on;
h0=plot(x,y,'b');hold on;
set(h0,'color',[0,0,0.6]);
end
h=plot(x3,y3,'b');hold on; set(h,'linewidth',3); set(h,'color',[0,0,0.6]); axis equal; axis off;