x = linspace(-3*pi,3*pi,50);
y = sin(x+1)./x;
plot(x,y);
[ymax,in] = max(y);
disp(ymax)
disp(y(in))
text(x(in),y(in),['\leftarrow y_{max} = '...
    num2str(ymax)],'FontSize',18)

axis([min(x) max(x) min(y)-0.2 max(y)+1])