x = linspace(-1,100,1000);
y = 2.^x;

plot(x,y)
title('Plot of y = 2^x')
hold on
plot(x(400), y(400), 'xr')

num = 1;
mylim = 10^num;

while (num <= 23)
    ylim([0 mylim])
    num = num + 1;
    mylim = 10^num;
    print([num2str(num) '.png'])
    pause
end