include fig0130; point w=l.A+1.5*l.v; draw(Label("$w$",EndPoint),l.A--w,Arrow); point wp=lp.A+1.5*lp.v; draw(Label("$w'$",EndPoint),lp.A--wp,Arrow); point ws=ls.A+1.5*ls.v; draw(Label("$w''$",EndPoint),ls.A--ws,Arrow); int n=64; real step=2pi/n; for (int i=0; i