raise RuntimeError("Can only multiply two ToeplitzLazyVariables if they correspond to the same grid.")
if self.J_left is not None:
if other.J_left is None:
raise RuntimeError("Cannot multiply interpolated ToeplitzLazyVariables by non-interpolated ones.")
if not (approx_equal(self.C_left, other.C_left) and approx_equal(self.C_right, other.C_right)):
raise RuntimeError("Cannot multiply two ToeplitzLazyVariables with different",
"left interpolation matrices.")
if self.added_diag is not None or other.added_diag is not None: