limk→1-⁡Ecνm⁡(z,k2)ⅆ⁡Ecνm⁡(z,k2)/ⅆ⁡z|z=0=limk→1-⁡Esνm+1⁡(z,k2)ⅆ⁡Esνm+1⁡(z,k2)/ⅆ⁡z|z=0=tanh⁡z(cosh⁡z)μ⁢F⁡(12⁢μ-12⁢ν+12,12⁢μ+12⁢ν+132;tanh2⁡z),