Latex formula normal and italic

latex The default formula is italicized , Sometimes you need proper body , It can be used \rm To modify . for example

    H=F_{ex}\left(Z\right)= W_{2}{\rm ReLU} (W_{1}Z),
 

\begin{align}
    H=F_{ex}\left(Z\right)= W_{2}{\rm ReLU} (W_{1}Z),
\end{align}

The displayed effect is （ Ignore blue fonts ）

summary ： Use a curly bracket {} Enclose the words that need to be typed , Add a front \rm that will do .