How to use the sgp4.api.Satrec.twoline2rv function in sgp4

def test_all_three_gravity_models_with_twoline2rv():
    # The numbers below are those produced by Vallado's C++ code.
    # (Why does the Python version not produce the same values to
    # high accuracy, instead of agreeing to only 4 places?)

    assert_wgs72old(Satrec.twoline2rv(LINE1, LINE2, WGS72OLD))
    assert_wgs72(Satrec.twoline2rv(LINE1, LINE2, WGS72))
    assert_wgs84(Satrec.twoline2rv(LINE1, LINE2, WGS84))

    # Not specifying a gravity model should select WGS72.

    assert_wgs72(Satrec.twoline2rv(LINE1, LINE2))

# ISS [Orbit 606], whose date is 2019 plus 366.82137887 days.
    # The core SGP4 routines handled this fine, but my hamfisted
    # attempt to provide a Python datetime for "convenience" ran
    # into an overflow.
    a = '1 25544U 98067A   19366.82137887  .00016717  00000-0  10270-3 0  9129'
    b = '2 25544  51.6392  96.6358 0005156  88.7140 271.4601 15.49497216  6061'
    correct_epoch = dt.datetime(2020, 1, 1, 19, 42, 47, 134368)

    # Legacy API.
    sat = io.twoline2rv(a, b, wgs72)
    assertEqual(sat.epoch, correct_epoch)

    correct_epoch = correct_epoch.replace(tzinfo=conveniences.UTC)

    # Modern API.
    sat = Satrec.twoline2rv(a, b)
    assertEqual(conveniences.sat_epoch_datetime(sat), correct_epoch)

def test_all_three_gravity_models_with_twoline2rv():
    # The numbers below are those produced by Vallado's C++ code.
    # (Why does the Python version not produce the same values to
    # high accuracy, instead of agreeing to only 4 places?)

    assert_wgs72old(Satrec.twoline2rv(LINE1, LINE2, WGS72OLD))
    assert_wgs72(Satrec.twoline2rv(LINE1, LINE2, WGS72))
    assert_wgs84(Satrec.twoline2rv(LINE1, LINE2, WGS84))

    # Not specifying a gravity model should select WGS72.

    assert_wgs72(Satrec.twoline2rv(LINE1, LINE2))

)

    it.reset()
    for itup in it:

        tle = itup[0]
        mjd = itup[2]

        size = mjd.shape[0]

        # TODO code path for api.accelerated == True

        for i in range(size):

            line1, line2 = tle[i].tle_strings()[1:]
            sat = Satrec.twoline2rv(line1, line2)
            _f, _i = np.modf(mjd[i])
            err_code, pos, vel = sat.sgp4(_i + 2400000.5, _f)

            if err_code:
                raise ValueError(
                    'Satellite propagation error', err_code,
                    '({})'.format(SGP4_ERRORS[err_code])
                    )

            eci_pos_x, eci_pos_y, eci_pos_z = pos
            eci_vel_x, eci_vel_y, eci_vel_z = vel

            itup[3][i][0] = eci_pos_x
            itup[3][i][1] = eci_pos_y
            itup[3][i][2] = eci_pos_z

Args:
        tle (array): two-line element string array.
        epoch_start (astropy.time.Time): starting epoch.
        epoch_end (astropy.time.Time): ending epich.
        step (float): step in Julian Day fractions.
        verbose (bool): debug output. Defaults to False.

    Returns:
        e (np.ndarray): vector of SGP4 error codes.
        r (np.ndarray): vector of satellite positions (TEME).
        v (np.ndarray): vector of satellite velocities (TEME).
        jd (np.ndarray): vector of Julian Day numbers.
        fr (np.ndarray): vector of Julian Day fractions.
    """

    satellite = Satrec.twoline2rv(tle[0], tle[1])

    fr = np.arange(epoch_start.jd2, epoch_end.jd2, step)
    jd = np.ones(fr.shape[0]) * epoch_start.jd1

    e, r, v = satellite.sgp4_array(jd, fr)

    return e, r, v, jd, fr