function  dv=tl(x,y)
dv=rect(10.*(x+0.1)).*rect(2*y)+rect(10.*(y-0.2)).*rect(5.*(x-0.05));
dv=dv+rect(10.*y).*rect(5.*(x-0.05))+rect(10.*(y+0.2)).*rect(5.*(x-0.05));