clear y1 y2;
y1(1) = 1e-10;
y2(1) = -1e-10;
nMax = 6;

for n=1:nMax
    y1(n+1) = 64 * y1(n) / (1 + y1(n))^3;
    y2(n+1) = 64 * y2(n) / (1 + y2(n))^3;
end;

n = 1:(nMax+1);
plot(n, y1, 'b-d', n, y2, 'r--o');
line([1, nMax+1], [0, 0], 'color', 'black', 'linewidth', 2, 'linestyle', ':');
title('y_{n+1}=64 y_n / (1 + y_n)^3: y_{eq}=0 is monotonically unstable');
xlabel('n'); ylabel('y_n');
legend('y_0 = 10^{-10}', 'y_0 = -10^{-10}', 'y_{eq}=0', 'Location', 'Best');