TeX Quellcode:

\begin{array}{rcl}f'_{yy}(x,y) &=& -\dfrac{5}{9}\sin(y)\cdot e^{\sin(x)+\sin(y)}+\dfrac{5}{9}\cos(y)e^{\sin(x)+\sin(y)}\cdot\cos(y) \\\\&=& -\dfrac{5}{9}\sin(y)e^{\sin(x)+\sin(y)}+\dfrac{5}{9}\cos^2(y)e^{\sin(x)+\sin(y)} \\\\&=& \dfrac{5}{9}e^{\sin(x)+\sin(y)}\left(-\sin(y)+\cos^2(y)\right)\end{array}