The Lorenz attractor is a set of chaotic solutions to the system of ordinary differential equations called the Lorenz equations. The plot of the attractor resembles a butterfly.
Python code:
#Lorenz Attractor
#http://journals.ametsoc.org/doi/abs/10.1175/1520-0469%281963%29020%3C0130%3ADNF%3E2.0.CO%3B2
import numpy as np
import matplotlib.pyplot as plt
from mpl_toolkits.mplot3d import Axes3D
def lorenz(x, y, z, s=10, r=28, b=2.667) :
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
dt = 0.01
stepCnt = 10000
#initial values
xs = np.empty((stepCnt + 1,))
ys = np.empty((stepCnt + 1,))
zs = np.empty((stepCnt + 1,))
xs[0], ys[0], zs[0] = (0., 1., 1.05)
for i in range(stepCnt) :
#ODE system
x_dot, y_dot, z_dot = lorenz(xs[i], ys[i], zs[i])
xs[i + 1] = xs[i] + (x_dot * dt)
ys[i + 1] = ys[i] + (y_dot * dt)
zs[i + 1] = zs[i] + (z_dot * dt)
fig = plt.figure()
ax = fig.gca(projection=’3d’)
ax.plot(xs, ys, zs)
ax.set_xlabel(“X Axis”)
ax.set_ylabel(“Y Axis”)
ax.set_zlabel(“Z Axis”)
ax.set_title(“Lorenz Attractor”)
plt.show()
Joshua Elkington
Harvard College
qparticle 