\normalsize}} U_{2}( \gamma_{1}, \gamma_{2}, \gamma_{3}, t )\; -\; \nonumber \\ 
\nonumber\\
-\;\frac{\gamma_{2}}{\gamma_{1}}\, U_{1}( \gamma_{1}, \gamma_{2}, \gamma_{3}, t) {\mbox{\large ] \normalsize}}   + \; {\mbox{\large [ \normalsize}} \tilde{F}_{2}( \gamma_{1}, \gamma_{2}, \gamma_{3}, t )\; -\;\frac{\gamma_{2}}{\gamma_{1}} \, \tilde{F}_{1}( \gamma_{1}, \gamma_{2}, \gamma_{3}, t) {\mbox{\large ] \normalsize}} 
\quad\quad\quad\quad\quad\quad \end{aligned}$$

$$\begin{aligned}
\label{eqn142}
\frac{d}{dt} {\mbox{\large [ \normalsize}}  U_{3}( \gamma_{1}, \gamma_{2}, \gamma_{3}, t )\; -\;\frac{\gamma_{3}}{\gamma_{1}}\, U_{1}( \gamma_{1}, \gamma_{2}, \gamma_{3}, t) {\mbox{\large ] \normalsize}} \;= -\nu( \gamma_{1}^{2} +\gamma_{2}^{2} +\gamma_{3}^{2}) {\mbox{\large [ \normalsize}} U_{3}( \gamma_{1}, \gamma_{2}, \gamma_{3}, t )\; -\; \nonumber \\ 
\nonumber\\
-\;\frac{\gamma_{3}}{\gamma_{1}}\, U_{1}( \gamma_{1}, \gamma_{2}, \gamma_{3}, t) {\mbox{\large ] \normalsize}}   + \;{\mbox{\large [ \normalsize}} \tilde{F}_{3}( \gamma_{1}, \gamma_{2}, \gamma_{3}, t )\; -\;\frac{\gamma_{3}}{\gamma_{1}}\, \tilde{F}_{1}( \gamma_{1}, \gamma_{2}, \gamma_{3}, t) {\mbox{\large ] \normalsize}} 
\quad\quad\quad\quad\quad\quad \end{aligned}$$

$$\label{eqn143}
\gamma_{1} U_{1}( \gamma_{1}, \gamma_{2}, \gamma_{3}, t ) \;+\; \gamma_{2}\, U_{2}( \gamma_{1}, \gamma_{2}, \gamma_{3}, t ) \;+\; \gamma_{3}\, U_{3}( \gamma_{1}, \gamma_{2}, \gamma_{3}, t ) \;=\;0$$

$$\label{eqn144}
U_{1}(\gamma_{1}, \gamma_{2},  \gamma_{3},  0)\;=\; U_{1}^{0}(\gamma_{1} ,\gamma_{2} ,\gamma_{3})$$

$$\label{eqn145}
U_{2}(\gamma_{1}, \gamma_{2},  \gamma_{3},  0)\;=\; U_{2}^{0}(\gamma_{1} ,\gamma_{2} ,\gamma_{3})$$

$$\label{eqn146}
U_{3}(\gamma_{1}, \gamma_{2},  \gamma_{3},  0)\;=\; U_{3}^{0}(\gamma_{1} ,\gamma_{2} ,\gamma_{3})$$

On the **third step** we use Laplace transform $(\ref{A4}), (\ref{A5})$ for a system of linear ordinary differential equations with constant coefficients $(\ref{eqn141})\;-\; (\ref{eqn143})\;$ and have as a result the system of linear algebraic equations with constant coefficients:

$$U_{k}^{\otimes} (\gamma_{1}, 