# Vertical spacing outside multline environment

When using multline for parsing an equation, there's a larger vertical space above the equation than below. Why is this? It looks off. Example:

\documentclass{article}
\usepackage{amsmath}
\usepackage{lipsum}
\begin{document}

\lipsum[2]

\begin{multline}
{I_{xx,\,\mathrm{frus}}} = {I_{xx,\,\mathrm{hemi}}} - {I_{xx,\,\mathrm{cap}}} \\ - \left({V_{\mathrm{cap}}} m_{\mathrm{frus}} {V_{\mathrm{frus}}}^{-1}\right) {\left( {{{\bar z}_{\mathrm{cap}}} - {{\bar z}_{\mathrm{hemi}}}} \right)^2} - m_{\mathrm{frus}} {\left( {{{\bar z}_{\mathrm{frus}}} - {{\bar z}_{\mathrm{hemi}}}} \right)^2}
\end{multline}

\lipsum[3]

\end{document}


Output:

Remove the blank line before the multline environment. It causes the previous paragraph to end, and a bigger vertical space is the result.
• By the way, \lipsum[2] will end the paragraph nonetheless and the blank line actually does nothing. With normal text, however, the blank line should be removed as you say. – egreg Feb 14 at 11:49
• @egreg I thought it might too, but I experimented before I posted: On my system, \lipsum[2] does not end the paragraph, as verified by adding zzz directly after \lipsum[2]. (TeX Live 2018, updated in the past week; and lipsum.sty says \ProvidesExplPackage{lipsum}{2019/01/02}{2.2}{150 paragraphs of Lorem Ipsum dummy text}. Do you have a different version? – Harald Hanche-Olsen Feb 14 at 13:53
• I forgot that the new version adds \par at the beginning – egreg Feb 14 at 16:32