m = np.random.rand(3)
x = np.random.rand(3)
y = np.random.rand(3)
u = np.random.rand(3)
v = np.random.rand(3)

import numpy as np
import matplotlib.pyplot as plt
from matplotlib import animation
m = np.random.rand(3)
x = np.random.rand(3)
y = np.random.rand(3)
u = np.random.rand(3)
v = np.random.rand(3)
fig = plt.figure(figsize=(12,12))
ax = fig.add_subplot(xlim=(-2e11,2e11),ylim=(-2e11,2e11))
ax.grid()
trace0, = ax.plot([],[],'-', lw=0.5)
trace1, = ax.plot([],[],'-', lw=0.5)
trace2, = ax.plot([],[],'-', lw=0.5)
pt0, = ax.plot([x[0]],[y[0]] ,marker='o')
pt1, = ax.plot([x[0]],[y[0]] ,marker='o')
pt2, = ax.plot([x[0]],[y[0]] ,marker='o')
k_text = ax.text(0.05,0.85,'',transform=ax.transAxes)
textTemplate = 't = %.3f days\n'
N = 1000
dt = 36000
ts =  np.arange(0,N*dt,dt)/3600/24
xs,ys = [],[]
for _ in ts:
    x_ij = (x-x.reshape(3,1))
    y_ij = (y-y.reshape(3,1))
    r_ij = np.sqrt(x_ij**2+y_ij**2)
    for i in range(3):
        for j in range(3):
            if i!=j :
                u[i] += (m[j]*x_ij[i,j]*dt/r_ij[i,j]**3)
                v[i] += (m[j]*y_ij[i,j]*dt/r_ij[i,j]**3)
    x += u*dt
    y += v*dt
    xs.append(x.tolist())
    ys.append(y.tolist())
xs = np.array(xs)
ys = np.array(ys)
def animate(n):
    trace0.set_data(xs[:n,0],ys[:n,0])
    trace1.set_data(xs[:n,1],ys[:n,1])
    trace2.set_data(xs[:n,2],ys[:n,2])   
    pt0.set_data([xs[n,0]],[ys[n,0]])
    pt1.set_data([xs[n,1]],[ys[n,1]])
    pt2.set_data([xs[n,2]],[ys[n,2]])
    k_text.set_text(textTemplate % ts[n])
    return trace0, trace1, trace2, pt0, pt1, pt2, k_text
ani = animation.FuncAnimation(fig, animate, 
    range(N), interval=10, blit=True)
plt.show()
ani.save("3.gif")

m = np.ones(3)
r = np.ones(3)
theta = np.arange(3)*np.pi*2/3
x = r*np.cos(theta)
y = r*np.sin(theta)
V = np.random.rand(N)
u = V*np.sin(theta)
v = V*np.cos(theta)