# Path: tecs/sat/datum.py
# C20 = -1082.63e-6


from math import sqrt
from tecs.sat import datum
    Returns
    -------
    x : float
        X, meters
    y : float
        Y, meters
    z : float
        Z, meters
    """

    # meters
    x0 = eph[0] * 1000
    vX = eph[1] * 1000
    aX = eph[2] * 1000

    y0 = eph[4] * 1000
    vY = eph[5] * 1000
    aY = eph[6] * 1000

    z0 = eph[8] * 1000
    vZ = eph[9] * 1000
    aZ = eph[10] * 1000

    if dt == 0:
        return x0, y0, z0

    r = sqrt(x0 ** 2 + y0 ** 2 + z0 ** 2)

    # - GLONASS ICD ver 5.1, 2008.
    first_sd = -(datum.mu / r ** 3)

# Path: tecs/sat/datum.py
# C20 = -1082.63e-6


# Path: tecs/sat/geo.py
from math import sqrt
from tecs.sat import datum

    Returns
    -------
    x : float
        X, meters
    y : float
        Y, meters
    z : float
        Z, meters
    """

    # meters
    x0 = eph[0] * 1000
    vX = eph[1] * 1000
    aX = eph[2] * 1000

    y0 = eph[4] * 1000
    vY = eph[5] * 1000
    aY = eph[6] * 1000

    z0 = eph[8] * 1000
    vZ = eph[9] * 1000
    aZ = eph[10] * 1000

    if dt == 0:
        return x0, y0, z0

    r = sqrt(x0 ** 2 + y0 ** 2 + z0 ** 2)

    # - GLONASS ICD ver 5.1, 2008.
    first_sd = -(datum.mu / r ** 3)

    second_sd = 3 / 2. * datum.J0sqd * datum.mu * datum.ae ** 2 / r ** 5