修复额外的空间并对齐整个方程

Question

请帮我对齐整个等式并删除多余的空格\underbrace。我用了\mathclap，\makebox[]但它看起来仍然很丑。谢谢帮助！

\begin{equation} \label{eq1}
    \begin{split}
     d^{connection}_{j} & =  \sqrt{\smash[b]{{{\bigg(x_0 \pm \sqrt {\smash[b]{r^2-\underbrace{\strut y_0^2}_
        {%}
        \textstyle
        \begin{array}{c}
          y_j^2
        \end{array}}
     -y_j^2+2\underbrace{\strut y_0}_
        {%}
        \textstyle
        \begin{array}{c}
          y_j
        \end{array}}y_j}} - \underbrace{\strut x_j}_
        {%}
        \textstyle
        \begin{array}{c}
          x_j \pm d_j^{\text{while waiting 0}}
        \end{array}}
        \bigg)^2}}}} 
    \end{split}
    \end{equation}

Answer 1

您可能想考虑以不同的方式来表达您的表达。

\documentclass{article}

\usepackage{mathtools}

\newcommand*\smashedunderbrace[2][]{\mathpalette\dosmashedunderbrace{{#2}{#1}}}
\newcommand*\dosmashedunderbrace[2]{\dosmashedunderbraceindeed{#1}#2}
\newcommand*\dosmashedunderbraceindeed[3]{%
  \smash[b]{%
    \ooalign{
      $#1#2$\cr
      \hidewidth$#1\underbrace{\phantom{#2}}_{#3}$\hidewidth\cr
    }%
  }%
}

\begin{document}

\begin{equation}
  \label{eq1}
  d^{\text{connection}}_{j} = \sqrt{
    \biggl(
    x_0 + \sqrt{r^2 - \smashedunderbrace[y_j^2]{y_0^2} - y_j^2 + 2 \smashedunderbrace[y_j]{y_0} y_j}
    - \smashedunderbrace[\qquad x_j \pm d_j^{\text{while waiting 0}}]{x_j}
    \;\biggr)^2
  }
\end{equation}

\end{document}

Answer 2

我建议你放弃\sqrt术语，改用(...)^{1/2}符号。这样，包装器array和指令都不再\smash[b]需要，因此可以省略，从而大大简化代码。请使用^{}术语来确保各种下标都以相同的深度排版。

\documentclass{article}
\usepackage{mathtools} % for '\mathclap' directive; loads 'amsmath' automatically
\begin{document}
\begin{equation} \label{eq1}
     d^{\,\text{connection}}_{j} = \bigl\{\bigl[x_0 \pm 
     ( r^2-\underbrace{y_0^2}_{y_j^2} {}-y_j^2
       +2\underbrace{y_0^{}}_{y_j^{\vphantom{2}}} y_j^{} )^{1/2} 
     - \underbrace{x_j}_{\mathclap{x_j^{}\pm d_j^{\,\text{while waiting 0}}}}
        \,\bigr]^2
     \bigr\}^{1/2}
\end{equation}
\end{document}