[fWalkOffAngleS, fWalkOffAngleF] = getWalkOffAngles(obj, vWavelengths, fTheta, fPhi)
     [fWalkOffAngleE] = getWalkOffAngles(obj, vWavelengths, fTheta)
 
    deprecated:
     [fWalkOffAngleE, fWalkOffAngleE] = getWalkOffAngles(obj, vWavelengths, fTheta)
    for back compatibility gives twice the same value.