problema gather

perchè così compila:

`\begin{equation}
x) \quad \rho \left(u \frac{\partial u}{\partial x} +v \frac{\partial u}{\partial y}\right)=-\frac{\partial p}{\partial x}+\frac{\partial \tau_{xx}}{\partial x} + \frac{\partial \tau_{yx}}{\partial y}
\end{equation}

\begin{equation}
y) \quad \rho \left(u \frac{\partial v}{\partial x} +v \frac{\partial v}{\partial y}\right)=-\frac{\partial p}{\partial y}+\frac{\partial \tau_{xy}}{\partial x} + \frac{\partial \tau_{yy}}{\partial y}
\end{equation}`

e così

`\begin{gather}
x) \quad \rho \left(u \frac{\partial u}{\partial x} +v \frac{\partial u}{\partial y}\right)=-\frac{\partial p}{\partial x}+\frac{\partial \tau_{xx}}{\partial x} + \frac{\partial \tau_{yx}}{\partial y} \\

y) \quad \rho \left(u \frac{\partial v}{\partial x} +v \frac{\partial v}{\partial y}\right)=-\frac{\partial p}{\partial y}+\frac{\partial \tau_{xy}}{\partial x} + \frac{\partial \tau_{yy}}{\partial y}
\end{gather}`

da

Runaway argument?
x) \quad \rho \left (u \frac {\partial u}{\partial x} +v \frac {\partial \ETC.
! Paragraph ended before \gather was complete.

\par
l.53

?

Process has been terminated …

grazie