我怎样才能改变定理中的行距？

Question

我正在使用该amsthm包。我需要仅在定理环境中更改所有定理正文中段落行之间的间距，而不更改报告的其他部分。

我该如何定义\newtheoremstyle这个目的？或者任何其他选择？

\documentclass[a4paper,fleqn]{report}‎‎
\usepackage{amsthm,amssymb,amsmath} ‎
\begin{document}‎           % Writing math‎
\theoremstyle{plain}
\newtheorem{theorem}{Theorem}‎[chapter]‎
\begin{theorem}‎‎
Balah Blah Blah 
Balah Blah Blah
Balah Blah Blah
Balah Blah Blah
Balah Blah Blah
Balah Blah Blah
Balah Blah Blah
Blah Blah   %How to increase between lines?
\end{theorem}
\end{document}

Answer 1

修改普通样式的参数，（参见egreg 的这个答案），您可以从包中添加\onehalfspacing（或\doublespacing）setspace。

\documentclass[a4paper,fleqn]{report}
\usepackage{setspace}
\usepackage{amsthm,amssymb,amsmath}

\newtheoremstyle{myplain}
  {\topsep}   % ABOVESPACE
  {\topsep}   % BELOWSPACE
  {\itshape\onehalfspacing}  % BODYFONT
  {0pt}       % INDENT (empty value is the same as 0pt)
  {\bfseries} % HEADFONT
  {.}         % HEADPUNCT
  {5pt plus 1pt minus 1pt} % HEADSPACE
  {}       
\theoremstyle{myplain}
\newtheorem{theorem}{Theorem}[chapter]

\usepackage{mwe}% only for testing

\begin{document} 
\chapter{A Chapter}
\section{A Section}
\blindtext%only for testing
\begin{theorem}
Balah Blah Blah 
Balah Blah Blah
Balah Blah Blah
Balah Blah Blah
Balah Blah Blah
Balah Blah Blah
Balah Blah Blah
Balah Blah Blah 
Balah Blah Blah
Balah Blah Blah
Balah Blah Blah
Balah Blah Blah
Balah Blah Blah
Balah Blah Blah
Blah Blah
\end{theorem}
\blindtext%only for testing
\end{document}

编辑：我不知道如何以厘米为单位精确设置行距，但您可以输入您想要的任何值\setstretch{...}。

\documentclass[a4paper,fleqn]{report}
\usepackage{setspace}
\usepackage{amsthm,amssymb,amsmath}

\newtheoremstyle{myplain}
  {-\baselineskip\topsep}   % ABOVESPACE
  {\topsep}   % BELOWSPACE
  {\itshape\setstretch{2}}  % BODYFONT
  {0pt}       % INDENT (empty value is the same as 0pt)
  {\bfseries} % HEADFONT
  {.}         % HEADPUNCT
  {5pt plus 1pt minus 1pt} % HEADSPACE
  {}       
\theoremstyle{myplain}
\newtheorem{theorem}{Theorem}[chapter]

\usepackage{mwe}% only for testing

\begin{document} 
\chapter{A Chapter}
\section{A Section}
\blindtext%only for testing
\begin{theorem}
Balah Blah Blah 
Balah Blah Blah
Balah Blah Blah
Balah Blah Blah
Balah Blah Blah
Balah Blah Blah
Balah Blah Blah
Balah Blah Blah 
Balah Blah Blah
Balah Blah Blah
Balah Blah Blah
Balah Blah Blah
Balah Blah Blah
Balah Blah Blah
Blah Blah
\end{theorem}
\blindtext%only for testing
\end{document}