function shili13h0=figure('toolbar','none',...    'position',[200 150 450 250],...    'name','实例13');[th,r]=meshgrid((0:10:360)*pi/180,0:0.05:1);[x,y]=pol2cart(th,r);z=x+i*y;f=(z.^4-1).^(0.25);contour(x,y,abs(f),20)axis equalxlabel('实部','fontsize',16);ylabel('虚部','fontsize',16);h=polar([0 2*pi],[0 1]);delete(h)hold oncontour(x,y,abs(f),20)