插入零高度换行符

Question

我有以下内容

\documentclass[12pt,a4paper]{article}
\begin{document}
\begin{align}
 a_{m,m} &\overset{(\eqref{eq:masssplitAIndex},\eqref{eq:masssplitLinvIndex})}{=} 1 - a \\
 &\overset{
  \substack{\eqref{eq:masssplitLinvIndex} \\ % too much space here
            \hphantom{\meqref{eq:masssplitAIndex,eq:masssplitLinvIndex}}
            }
          }
  }{=} 1 - a.
 \end{align}

\结束{文档}

将幻影框堆叠（零跳过）在图中（0.33）上方以使等号的间距正确的正确解决方案是什么？）

Answer 1

以下示例使用\stackrel将引用放在等号上方。第二行的虚线是通过设置的，\ooalign以避免明确测量上一个等式的引用。

\documentclass[12pt,a4paper]{article}
\usepackage{amsmath}
\usepackage{hyperref}
\numberwithin{equation}{section}

\begin{document}
\setcounter{equation}{32}
\begin{gather}
  \label{eq:masssplitLinvIndex}
  \text{mass split L inv index}
\\
  \label{eq:masssplitAtIndex}
  \text{mass split at index}
\end{gather}

\begin{align}
  a_{m,m}
  & \stackrel{(\ref{eq:masssplitAtIndex},\,\ref{eq:masssplitLinvIndex})}{=}
  1
\\
  & \stackrel{%
      \ooalign{%
        \phantom{%
          $\scriptstyle
          (\ref{eq:masssplitAtIndex},\,\ref{eq:masssplitLinvIndex})$%
        }\cr
        \hfil$\scriptstyle(\ref{eq:masssplitLinvIndex})$\hfil
      }%
    }{=}
  1
\end{align}
\end{document}

Answer 2

您可以alignat与 hack 一起使用来使列内容居中：

\documentclass{article}
\usepackage{amsmath,amssymb}

\numberwithin{equation}{section}

\makeatletter
\newcommand{\Cen}[2]{%
  \ifmeasuring@
    #2%
  \else
    \makebox[\ifcase\expandafter #1\maxcolumn@widths\fi]{$\displaystyle#2$}%
  \fi
}
\makeatother

\begin{document}

\setcounter{equation}{32}
\begin{gather}
x\label{eq:masssplitAIndex}\\
y\label{eq:masssplitLinvIndex}
\end{gather}

Now the main thing:
\begin{alignat}{2}
 a_{m,m} &\Cen{2}{\overset{(\ref{eq:masssplitAIndex},\ref{eq:masssplitLinvIndex})}{=}{}} && 1 - a \\
 &\Cen{2}{\overset{\eqref{eq:masssplitLinvIndex}}{=}}&& 1 - a.
\end{alignat}

\end{document}

看https://tex.stackexchange.com/a/209732/4427为了\Cen

然而，我更喜欢简单一点的东西：

\begin{alignat}{2}
a_{m,m} &= 1-a &&\qquad\text{by (\ref{eq:masssplitAIndex}, \ref{eq:masssplitLinvIndex})} \\
        &= 1-a &&\qquad\text{by \eqref{eq:masssplitLinvIndex}}
\end{alignat}