# Why does \left| insert unecessary vertical space below its argument?

When using \left| and \right| to typeset absolute value, I get unnecessary space as follows

\documentclass[11pt, a4paper]{IEEEtran}

\usepackage{amsmath}
\usepackage{amssymb, amsfonts}

\begin{document}

$$SDSCR_{i} = \frac{\left| V_{R, \thinspace i} \right|^{2}}{ \left| S_{eq, \thinspace i}^{\adjustbox{raise=0.1\baselineskip}{*}} \right| \left| Z_{RR, \thinspace ii} \right|}$$

\end{document}

• That is because delimiters are symmetric w.r.t. the math axis, and there is only a discrete set of sizes – Bernard Jan 18 at 19:46
• Why do you raise the * superscript even higher? That the main cause... – Werner Jan 18 at 19:49
• @Werner For aesthetics because the variable would look crowded. – Al-Motasem Aldaoudeyeh Jan 18 at 19:52
• If SDSCR is an identifier/variable, it should not be typeset in math italic -- it looks awful that way – Christian Hupfer Jan 18 at 19:57
• @ChristianHupfer. Most people here seem to not like italic math, but in electrical engineering, italic math for variables and even subscripts somtimes is the norm. – Al-Motasem Aldaoudeyeh Jan 18 at 20:03

delimiters are centred on the math axis, so by making the * extra high you are forcing the delimiters to have extra depth, but it is usually better to use fixed size delimiter. Also never use the math italic font for multi-letter identifiers;

\documentclass[11pt, a4paper]{IEEEtran}

\usepackage{amsmath}
\usepackage{amssymb, amsfonts}

\begin{document}

$$\mathit{SDSCR}_{i} = \frac{\bigl| V_{\mathit{f}R, i} \bigr|^{2}}{ \bigl| S_{\mathit{eq}, i}^{*} \bigr| \bigl| Z_{\mathit{RR}, ii} \bigr|}$$

\end{document}