# Additional vertical space in an equation

I have this equation:

\begin{equation}
\mathbf{S}_o = \frac{ \sum\limits_{i=1}^{N} \left[ \left( \frac{\sum\limits_{k=1}^{J-1} \frac{\| P_k^Q - P_{k+1}^Q  \|}{\| P_k^T - P_{k+1}^T   \|}  }{J-1} \right) \cdot \mathbf{S}_i \right]   }{N}
\end{equation}


Being rendered like this: I don't understand why there is that additional space there ?

• Why those parentheses? They aren't needed. Jun 14 '13 at 13:44
• I don't think they should leave this space there ? Jun 14 '13 at 13:52
• BTW: It is really $S_o$, not $S_0$? Jun 14 '13 at 13:52
• The main fraction line is centered with respect to the summation symbol. Jun 14 '13 at 13:55
• The brackets are centered with respect to the middle line of the middle level fraction. Removing all the large unncessary brackets, removes the space you see, but egreg suggested rewriting below is much better. Jun 14 '13 at 14:03

You don't need those parentheses. But that way of typesetting the formula is heavy and doesn't add to clarity.

Here's my proposals: the second one is surely how I'd typeset the formula.

\documentclass{article}
\begin{document}

\begin{equation}
\mathbf{S}_o =
\frac{\sum\limits_{i=1}^{N}
\frac{\sum\limits_{k=1}^{J-1} \frac{\| P_k^Q - P_{k+1}^Q \|}{\| P_k^T - P_{k+1}^T \|}}{J-1}
\cdot \mathbf{S}_i}{N}
\end{equation}

\begin{equation}
\mathbf{S}_0 =
\frac{1}{N}
\sum_{i=1}^{N}\biggl(
\frac{1}{J-1}
\sum_{k=1}^{J-1}
\frac{\| P_k^Q - P_{k+1}^Q  \|}{\| P_k^T - P_{k+1}^T \|} \cdot \mathbf{S}_i
\biggr)
\end{equation}
\end{document} Note that you probably want a 0 at the left hand side, rather than "oh".

• Your second is a pretty good one Jun 14 '13 at 13:55