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:

http://www.physicsforums.com/showthread.php?t=63809

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.

Thanks in advance….

## Best Answer

Try

Or if you have

`\usepackage{amsmath}`

, you can use`\rvert`

instead of the`|`

. In fact, this is probably the better way to go.