Customizing math symbol “evaluated at” - Vertical bar growing up only below

I'd like to customize the math symbol "evaluated at". If I use the code:

\documentclass[11pt]{article}
\usepackage{amsmath}

\begin{document}

\begin{equation*}
\frac{d}{dt} \left( i_{O_L} \Bigr|_{O_G} \right) =
\end{equation*}

\begin{equation*}
\frac{d}{dt} \left( i_{O_L} \Bigg\rvert_{O_G} \right) =
\end{equation*}

\end{document}


In the first case the vertical bar is too small. In the second case the vertical bar grows up in both directions up and down. I'm wondering if it's possible to grow up the bar only below. For example (i want a thin vertical bar, in fugure it is not so thin):

EDIT:

Thank you so much for your time.

• Your notations look strange.What's evaluated? The derivative or the argument of the differential symbol? – Bernard Jan 24 '19 at 18:34
• Hello @Bernard see the edit please. I want only the symbol evaluated at like the above one. – Gennaro Arguzzi Jan 24 '19 at 22:47
• So inside the parentheses? – Bernard Jan 24 '19 at 22:52
• ...like in the figure. Without parentheses. – Gennaro Arguzzi Jan 24 '19 at 23:00
• Ps: if there is the option to put the above expression inside paretheses, it would be better. – Gennaro Arguzzi Jan 24 '19 at 23:04

Not too sure I've well ubderstood what you want, but I propose this:

\documentclass[11pt]{article}
\usepackage{amsmath}
\usepackage{diffcoeff, array, delarray}

\begin{document}

\begin{equation*}
\diffp*{\begin{array}[t]({@{}c@{\,}|@{\,}c@{}})O_L & \\ & O_T\end{array}}{t}
\end{equation*}

\begin{equation*}

\end{document}


Fix the depth by changing the value 5ex to something more sensible. Be advised that delimiters using \left and \right will grow as much in the upper as in the lower direction.

• Hi @egreg, thank you very much for your solution. – Gennaro Arguzzi Jan 25 '19 at 10:18