\[I_{\nu}\left(\nu z\right)=\frac{e^{\nu\eta}}{(2\pi\nu)^{\frac{1}{2}}(1+z^{2})^%
{\frac{1}{4}}}\left(\sum_{k=0}^{\ell-1}\frac{U_{k}(p)}{\nu^{k}}+O\left(\frac{1%
}{z^{\ell}}\right)\right),\]