为什么这些矩阵的垂直尺寸不同？

Question

我对这两个矩阵的垂直大小有一些问题，如下面的 MWE 代码所示：

\documentclass[11pt,letterpaper,twoside]{book}
\usepackage[T1]{fontenc}
\usepackage{lmodern}
\usepackage[total={6in,10in},left=1.5in,top=0.5in,includehead,includefoot]{geometry}
\usepackage{microtype}
\usepackage{amsmath}
\usepackage{amsfonts}
\usepackage{upgreek}

\begin{document}

%\setlength{\abovedisplayskip}{1em}
\setlength{\abovedisplayshortskip}{0pt}
\setlength{\belowdisplayskip}{\abovedisplayskip}
\setlength{\belowdisplayshortskip}{\belowdisplayskip}
\setlength{\jot}{3ex}

\begin{align}
    A &=
    \left[ \begin{array}{c}
        \phi \\[3ex]
        \displaystyle{\frac{\boldsymbol{\upsigma} \cdot \mathbf{p}}{E + m}} \: \phi
    \end{array} \right]
    \\
    B &=
    \left[ \begin{array}{c}
        \displaystyle{\frac{\boldsymbol{\upsigma} \cdot \mathbf{p}}{E - m}} \: \chi \\[3ex]
        \chi
    \end{array} \right]
\end{align}

\end{document}

预览：

矩阵 B 比 A 短，为什么？我想让两个矩阵的大小完全相同。怎么做？

使用矩阵环境没有帮助。

Answer 1

您tabularray可以设置行高：

\documentclass[11pt,letterpaper,twoside]{book}
\usepackage[T1]{fontenc}
\usepackage{lmodern}
\usepackage[total={6in,10in},left=1.5in,top=0.5in,includehead,includefoot]{geometry}
\usepackage{microtype}
\usepackage{amsmath}
\usepackage{amsfonts}
\usepackage{upgreek}

\usepackage{tabularray}
\UseTblrLibrary{amsmath}
\NewDocumentEnvironment{amatrix}{+b}{
    \begin{+bmatrix}[
        rowsep=0pt,
        rows={ht=6ex},
        column{1}={leftsep=4pt},
        column{Z}={rightsep=4pt}
        ]
        #1
    \end{+bmatrix}%
}{}  


\begin{document}
    
    %\setlength{\abovedisplayskip}{1em}
    \setlength{\abovedisplayshortskip}{0pt}
    \setlength{\belowdisplayskip}{\abovedisplayskip}
    \setlength{\belowdisplayshortskip}{\belowdisplayskip}
    \setlength{\jot}{3ex}
    

\begin{align}
    A &=
    \begin{amatrix}
        \phi \\
        \displaystyle{\frac{\boldsymbol{\upsigma} \cdot \mathbf{p}}{E + m}} \: \phi
    \end{amatrix} 
    \\
    B &=
    \begin{amatrix}
        \displaystyle{\frac{\boldsymbol{\upsigma} \cdot \mathbf{p}}{E - m}} \: \chi \\
        \chi
    \end{amatrix} 
\end{align}

\end{document}