# [Tex/LaTex] How to get a vertical bar which is longer than \mid

math-modesymbols

sometimes when writing mathematical expression with partial derivatives, one needs to write a vertical bar afterwards and write the value at the which the partial derivatives are being computed as subscripts. See for example the bottom post here:

However, the \mid symbol doesn't produce a tall bar that corresponds to the size of the partial derivatives term. Is there a way to have a taller bar?

PS: Some other posts here mention \middle| but this doesn't compile on my computer.

\left.\frac{\partial f}{\partial x}\right|_{x_0}

Or if you have \usepackage{amsmath}, you can use \rvert instead of the |. In fact, this is probably the better way to go.