min max and range of the matrix: How to mathematically write that?

Question

I have two questions about mathematical notation.

1. Let F be the matrix of $i$ rows and $j$ columns. I want to found min and max values of that matrix for every row. Currently, I have this

$$l_i = \min\limits_{j \in \{1, ..., n\}} f_{ij}, \quad i = 1, ..., m, $$ $$u_i = \max\limits_{j \in \{1, ..., n\}} f_{ij}, \quad i = 1, ..., m, $$

Ideally, I would like to write this such that it would result in another matrix with two columns, one of lower bounds and the other one with the upper bounds. How would I write that? Any other suggestions to write this are greatly appreciated. Could you write it like this? \begin{equation} \textbf{D} = [\min\limits_{j \in \{1, ..., n\}} f_{ij}, \max\limits_{j \in \{1, ..., n\}} f_{ij}], \quad i = 1, ..., m. \end{equation}

2. How do you write mathematically the range between two column vectors with $m$ observations? I have this: $$\textbf{Rng} = |\min(\textbf{F}) - \max(\textbf{F}) |$$ Is this okay?