.. function:: py__obs_op_pdaf

    Apply observation operator

    This function computes :math:`\mathbf{H} \mathbf{x}`, where
    :math:`\mathbf{H}` is the observation operator and
    :math:`\mathbf{x}` is state vector.

    Parameters
    ----------
    step : int
        Current step
    dim_p : int
        Dimension of state vector
    dim_obs_p: int
        Dimension of observation vector
    state_p: np.ndarray[np.float, dim=1]
        State vector. shape: (dim_p,)
    m_state_p: np.ndarray[np.float, dim=1]
        Observed state vector. shape: (dim_obs_p,)

    Returns
    -------
    m_state_p: np.ndarray[np.float64, dim=1]
        Observed state vector. shape: (dim_obs_p,)