A Maple code is developed for the slender, flexible, compressed post-buckling bar. Its deformation curve shape is numerically simulated. Simulations and detailed solutions are given for two cases---the maximum deflection and the closing deflection curve after buckling. Mechanical character of instability after buckling is analyzed and computed. Analysis expression is given; the geometric features of the curve in the equilibrium case after buckling is analyzed and computed. The results indicate that the maximum deflection after buckling and the closing deflection curve are two completely different buckling states.