code: def Jwik(dW, h, n=5):
      
      m = dW.shape[1]
      Atilde, I = Iwik(dW, h, n)
      J = I + 0.5*h*np.eye(m).reshape((1, m, m))
      return (Atilde, J)
docs: matrix J approximating repeated Stratonovich integrals for each of N
      time intervals, using the method of Wiktorsson (2001).
  
      Args:
        dW (array of shape (N, m)): giving m independent Weiner increments for
          each time step N. (You can make this array using sdeint.deltaW())
        h (float): the time step size
        n (int, optional): how many terms to take in the series expansion
  
      Returns:
        (Atilde, J) where
          Atilde: array of shape (N,m(m-1)//2,1) giving the area integrals used.
          J: array of shape (N, m, m) giving an m x m matrix of repeated
          Stratonovich integral values for each of the N time intervals.