Equation Icon  √ -- √ -- √2-- -- uret = 2uB = 2G = τ − ---ξi(τ)Y01i(ζ,ζ ), (3.77 ) √ -- 2 --2- i 0 -- τ = uret + 2 ξ(uret)Y1i(ζ,ζ). (3.78 )