# How to automatically make symbols in equations less crowded?

As you can see in the pic above, some parts of the equation seem to be crowded. Here, the problem is fixed by using \thinspace command. Here is my MWE:

\documentclass{book}
\usepackage{amsmath}

\begin{document}

$$% V_{oc} = V_{oc,ref} \bigg[1 + \frac{\beta}{100} (T_{op}-T_{ref}) \biggl] + V_{oc,ref} \thinspace \varphi \thinspace ln \bigg( \frac{G_{op}}{G_{ref}} \bigg) % \label{eq:V_oc_trans}$$

$$% V_{oc} = V_{oc,ref} \bigg[1 + \frac{\beta}{100} (T_{op}-T_{ref}) \biggl] + V_{oc,ref} \varphi ln \bigg( \frac{G_{op}}{G_{ref}} \bigg) % \label{eq:V_oc_trans2}$$

\end{document}


Which returns:

The problem here is that typing \thinspace over and over is redundant. Can we overcome crowdedness by writing some command in the preamble or using a package option?

• the main problem is that you should not use math italic for multi-letter words (it spreads them out to make them not look like a word) use T_{\mathrm{ref}} and the same for op and oc – David Carlisle Jul 9 '17 at 19:59
• also you should use \biggl on the left and \biggr on the right (although I would use a smaller size here) – David Carlisle Jul 9 '17 at 20:01
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After looking at the equation, I see just one place where a thin space is needed, namely in front of \varphi. Note that the thin space is denoted by \,.

However, the subscript should be all \mathrm, because they're textual; \bigg should be either \biggl (opening) or \biggr (closing); ln should be \ln. The parentheses around the argument of the logarithm, which is a fraction, are not needed.

\documentclass{book}
\usepackage{amsmath}

\begin{document}

$$\label{eq:V_oc_trans} V_{\mathrm{oc}} = V_{\mathrm{oc},\mathrm{ref}} \biggl[1 + \frac{\beta}{100} (T_{\mathrm{op}}-T_{\mathrm{ref}}) \biggr] + V_{\mathrm{oc},\mathrm{ref}} \, \varphi \ln \frac{G_{\mathrm{op}}}{G_{\mathrm{ref}}}$$

\end{document}


The position of \label is actually immaterial, but placing it at the beginning helps to see it more easily.

Switching the position of \varphi may be another choice; this doesn't require \,: