# What command gives me the highlighted operator? [duplicate]

I need to write this equation in latex, but I don't know how to get the vertical line and the B subscript below it. If anyone knows the operator or command, it'd be very helpful.

With a structure \left-\right:
$\bar M_d = \left.\frac{d \bar H_B}{d t}\right|_B$

• \left\vert...\right\vert also produced the same result, but better spacing... – MadyYuvi Jul 22 '19 at 8:45
• @barbarabeeton The code $\left\vert \frac{a}{b}\right\vert$ will produce single vertical rule only, \Vert only produce two vertical lines... – MadyYuvi Jul 23 '19 at 5:07
• @MadyYuvi -- That's not what I meant. Only one vertical rule is requested, on only the right side. That would be encoded, using your formulation, as \left. ... \right\vert. – barbara beeton Jul 23 '19 at 13:32