t=-2:.02:2;y=atan(t);
set(0,'DefaultAxesFontName','times')
set(0,'DefaultAxesFontSize',16)
set(0,'DefaultTextFontName','times')
figure(1)
plot(t,y,'r-',[t(1) t(length(t))],[y(1) y(length(t))],'r--',t,t,'r-.')
xlabel('Input')
ylabel('Output')
axis([-2 2 -2 2])
axis('square')
grid
legend('Function','Lower bound','Upper bound')
