t=0:pi/1000:pi;y1=@(t) sin(t).*sin(9*t);y2=sin(t);plot(t,y1(t),t,y2'*[1 -1],'r--')hold on t0=linspace(0,pi,10);for i=1:length(t0)t00=fzero(y1,t0(i));plot(t00,0,'o')end plot(pi,0,'o')