Wn,4⁡(u,ξ)=|ξ|1/2⁢Yν⁡(u⁢|ξ|1/2)⁢(∑s=0n-1As⁡(ξ)u2⁢s+O⁡(1u2⁢n-1))-|ξ|⁢Yν+1⁡(u⁢|ξ|1/2)⁢(∑s=0n-2Bs⁡(ξ)u2⁢s+1+O⁡(1u2⁢n-2)).