message: Add registration for (A^-1)^-1 = A.
diff: @@ -40,6 +40,12 @@ def _inverse_linear_operator(linop):
  is_square=linop.is_square)
  +@linear_operator_algebra.RegisterInverse(
  + linear_operator_inversion.LinearOperatorInversion)
  +def _inverse_inverse_linear_operator(linop_inversion):
  + return linop_inversion.operator
  +
  +
  @linear_operator_algebra.RegisterInverse(
  linear_operator_diag.LinearOperatorDiag)
  def _inverse_diag(diag_operator):
  