Ketinit(); Setparent(Cdyname()+"fig"); Setketcindyjs(["No=all","Col=offwhite"]);//no ketjs Setwindow([-2.5,2.5],[-2.5,2.5]); Fontsize("n"); p0=[0,0]; r=2.5; Circledata("1",[p0,r],["dr,1.5","Num=100"]); an=Animationparam(0,60,[-100000,100000]); th=an*pi/180; p1=r*[cos(th),sin(th)]; Listplot("1",[p0,p1],["dr,1.5","Color=red"]); fun="(0.5+0.1*abs(t)/(2*pi))*[cos(t),sin(t)]"; rng=Assign("t=[0,th]",["th",th]); if(abs(th)>0, Paramplot("1",fun,rng); Arrowhead("1",Ptend(gp1),"gp1",[0.5]); ); Expr([-r,r],"e","\theta="+Sprintf(an,2)+"^{\circ}",["Size=1.5"]); Figpdf(); Windispg();