def snowpack_albedo(solutions, Gp, mu):
    """compute the albedo of the snowpack at one wavelength

    :param solutions: coefficients A et B pour chaque couche qui permttent calcul analytique des flux dans tous le manteau
    :type solutions: array
    :param Gp: coefficients Gm calculated for each layer
    :type Gp: array
    :param mu: cosine of the incident angle of intensity
    :ype mu:

    :returns: albedo at one wavelength (W/m^2)
"""
    if solutions is None:
        return 0
    solution_C = solutions[2]
    solution_D = solutions[3]
    albedo = (solution_C[0] + solution_D[0] + Gp[0]) / mu
    return albedo
