Yν′⁡(z)∼(2π⁢z)12⁢(cos⁡ω⁢∑k=0∞(-1)k⁢b2⁢k⁡(ν)z2⁢k-sin⁡ω⁢∑k=0∞(-1)k⁢b2⁢k+1⁡(ν)z2⁢k+1),