通过有限差分方程画分叉图。程序简单，运行时间短。-Painting by the finite difference equation bifurcation diagram. The program is simple and needs short running time.

绘制各种非线性振动图：分叉图、频谱、相图、poincare图、Lyapunov指数(All kinds of nonlinear vibration diagrams are drawn: bifurcation diagram, spectrum, phase diagram, poincare diagram, Lyapunov exponent.)