code: def s2a(s):
      
      a = np.zeros((3, 3,), 'f')  # make the a matrix
      for i in range(3):
          a[i][i] = s[i]
      a[0][1], a[1][0] = s[3], s[3]
      a[1][2], a[2][1] = s[4], s[4]
      a[0][2], a[2][0] = s[5], s[5]
      return a
docs: convert 6 element "s" list to 3,3 a matrix (see Tauxe 1998)