code: def calc_A(Ys):
      '''Return the matrix A from a list of Y vectors.'''
      return sum(np.dot(np.reshape(Y, (3,1)), np.reshape(Y, (1, 3)))
              for Y in Ysf calc_A(Ys):
      '''Return the matrix A from a list of Y vectors.'''
      return sum(np.dot(np.reshape(Y, (3,1)), np.reshape(Y, (1, 3)))
              for Y in Ys)
docs: Return the matrix A from a list of Y vectors.