$$\left. \begin{array} { l } { y _ { 1 } = \ln n ^ { - 1 } ( \tan \frac { u } { 2 } ) = \frac { u } { 2 } } \\ { y = a ^ { n } \cdot u ^ { a } \quad \frac { d y } { d n } } \end{array} \right.$$
$y_{1}=\ln(\frac{\tan(\frac{u}{2})}{n})$
$n\in \mathrm{R}$
$u\in \mathrm{R}$
