text: import numpy as np
  
  def evolution(X, U, m, Ixx, dt):
      g = 9.81 # m/s^2
  
      y       = X[0] + X[3]*dt
      z       = X[1] + X[4]*dt
      phi     = X[2] + X[5]*dt
      vy      = X[3] + (    - U[0] / m ) * np.sin(X[2]) * dt
      vz      = X[4] + ( -g + U[0] / m ) * np.cos(X[2]) * dt
      phi_dot = X[5] + U[1] / Ixx * dt
  
      return np.array([y, z, phi, vy, vz, phi_dot])