# Kerning with parentheses

Given the MWE below, one can see that the spacing around the parentheses is rather awkward. The opening parenthesis is too close to \cos and \sin, and too far away from the \omega. The closing parenthesis is too far away from \varphi. Is there a way to reduce/add some kerning?

\documentclass{standalone}

\usepackage[charter]{mathdesign}

\begin{document}
$\mathrm{e}^{\,\mathrm{j}(\omega t + \varphi)} =\cos (\omega t + \varphi) + \mathrm{j}\sin (\omega t + \varphi)$
\end{document}


Update: of cource one can use \kern to add kerning, but I'm looking for a more general way.

• Of course there are many ways to do so. But I think the spacing is by design. – user156344 Feb 18 at 8:22
• @JouleV Correct, but I don't like it. – Jesse op den Brouw Feb 18 at 8:26
• Are you looking for an automatic solution? The fact that you already used \, in the exponent makes me think that you know about the manual solution \sin (\!\omega t + \varphi\!) already. (You can pick different kerns than \! with \mkern -2mu, see for example tex.stackexchange.com/q/374021/35864) – moewe Feb 18 at 15:46
• @moewe: Yes I was looking for an automatic solution. I used the thin space because the superscript j was too close to e. If one uses i as the imaginary unit, then no thin space is needed. – Jesse op den Brouw Feb 18 at 16:43

If you wanted to automatically add some extra kerning to a glyph in text mode, then I'd tell you to look into microtype's \SetExtraKerning command. Unfortunately, that doesn't work in math mode. I think your best option is using the \mkern command made specifically to be used in math mode. Here's how it looks

\documentclass{standalone}
\usepackage[charter]{mathdesign}
\newcommand{\leftpar}{\mkern3mu(\mkern-3mu}
\newcommand{\rightpar}{\mkern-3mu)\mkern3mu}
\begin{document}
$\mathrm{e}^{\,\mathrm{j} \leftpar \omega t + \varphi \rightpar} =\cos \leftpar\omega t + \varphi\rightpar + \mathrm{j}\sin \leftpar\omega t + \varphi\rightpar$
\end{document}


Where mu stands for math units and it's defined as 1/18 of em.

• I came to that same conclusion. It's definitily this font, no problems in lmodern. – Jesse op den Brouw Feb 18 at 16:45