I am writing a big formula where a vertical line is needed. Instead of $\vline$ or $|$, does anyone know a way to draw this vertical line of desired length? The formula is something like

F_{m-1}\Big( \text{some big contents} \Big) |\: \mathcal{F}_1

Thank you very much!


2 Answers 2


Well, if you are manually defining the size, as in the example you could just put a \Bigg| at the right place. Probably better would be using \left, \middle and \right.

By the way: You should prefer \[ and \] instead of double $$.

\[ E\left[ F_{m-1}\Big( \text{some big contents} \Big) \middle|\: \mathcal{F}_1 \right] \]
  • 3
    just curious, why should we prefer [ to $$ ?
    – No One
    May 11, 2021 at 21:48

Try enclosing your expression into \left. and \right\vert, as in

\left.\frac{\partial L}{\partial\bm{\beta}}\right\vert_{\hat\beta}=-2\bm{X'y}+2\bm{X'X\hat\beta}=0

which yields:

alt text

  • 5
    Note that there is a dot in \left.. I wondered for a while why it didn't work. Jul 31, 2019 at 9:23
  • 2
    You tricky tricky you.
    – Fraïssé
    Feb 11, 2021 at 6:17

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