Python&数学基礎

カオス理論


プログラム(Python 3.10.4)


        import matplotlib.pyplot as plt
        import matplotlib.patches as patches
        import numpy as np
        import pandas as pd


        def lorenz(x, y , z, s=10, r=28, b=8/3):
            x_dot = s*(y - x)
            y_dot = r*x - y -x*z
            z_dot = x*y - b*z
            return [x_dot, y_dot, z_dot]


        def chaos():
            dt = 0.01
            xyz_ini = [0.0, 10.0, 50.0]
            num = 10000
            xs = np.empty(num)
            ys = np.empty(num)
            zs = np.empty(num)
            xs[0], ys[0], zs[0] = xyz_ini
            for i in range(1, num):
                x_dot, y_dot, z_dot = lorenz(xs[i-1], ys[i-1], zs[i-1])
                xs[i] = xs[i-1] + (x_dot * dt)
                ys[i] = ys[i-1] + (y_dot * dt)
                zs[i] = zs[i-1] + (z_dot * dt)
            fig_chaos = plt.figure()
            ax = fig_chaos.add_subplot(projection='3d')
            ax.plot(xs, ys, zs, lw=0.5)
            plt.show()