include Math                                

x = 1                                       
y = 0                                       
z = 0                                       
vx = 0                                      
vy = 0.5                                    
vz = 0                                      
dt = 0.01                                   

print(x, "  ", y, "  ", z, "  ")
print(vx, "  ", vy, "  ", vz, "\n")

1000.times{                                 
  r2 = x*x + y*y + z*z                      
  r3 = r2 * sqrt(r2)                        
  ax = - x / r3                             
  ay = - y / r3                             
  az = - z / r3                             
  x += vx*dt                                
  y += vy*dt                                
  z += vz*dt                                
  vx += ax*dt                               
  vy += ax*dt                               
  vz += az*dt                               
  print(x, "  ", y, "  ", z, "  ")          
  print(vx, "  ", vy, "  ", vz, "\n")       
}