添加

Question 1

人们可以很容易地使“大加号”的大小与以下相同\sum：

\documentclass{article}
\usepackage{amsmath}
\usepackage{graphicx}

\makeatletter
\newcommand{\bigplus}{%
  \DOTSB\mathop{\mathpalette\mattos@bigplus\relax}\slimits@
}
\newcommand\mattos@bigplus[2]{%
  \vcenter{\hbox{%
    \sbox\z@{$#1\sum$}%
    \resizebox{!}{0.9\dimexpr\ht\z@+\dp\z@}{\raisebox{\depth}{$\m@th#1+$}}%
  }}%
  \vphantom{\sum}%
}
\makeatother

\begin{document}

\begin{center}% test bounding box
\setlength{\fboxsep}{0pt}
\fbox{$\displaystyle\sum$} \fbox{$\displaystyle\bigplus$}
\end{center}

\[
\sum_{i=1}^m\bigplus_{j=1}^n\dots\bigplus_{k=1}^p x_{ijk}
\]
\begin{center}% to test text style
$\sum_{i=1}^m\bigplus_{j=1}^n\dots\bigplus_{k=1}^p x_{ijk}$
\end{center}

\LARGE % test for sizes
\[
\sum_{i=1}^m\bigplus_{j=1}^n\dots\bigplus_{k=1}^p x_{ijk}
\]
\begin{center}% to test text style
$\sum_{i=1}^m\bigplus_{j=1}^n\dots\bigplus_{k=1}^p x_{ijk}$
\end{center}

\end{document}

Answer

人们可以很容易地使“大加号”的大小与以下相同\sum：

\documentclass{article}
\usepackage{amsmath}
\usepackage{graphicx}

\makeatletter
\newcommand{\bigplus}{%
  \DOTSB\mathop{\mathpalette\mattos@bigplus\relax}\slimits@
}
\newcommand\mattos@bigplus[2]{%
  \vcenter{\hbox{%
    \sbox\z@{$#1\sum$}%
    \resizebox{!}{0.9\dimexpr\ht\z@+\dp\z@}{\raisebox{\depth}{$\m@th#1+$}}%
  }}%
  \vphantom{\sum}%
}
\makeatother

\begin{document}

\begin{center}% test bounding box
\setlength{\fboxsep}{0pt}
\fbox{$\displaystyle\sum$} \fbox{$\displaystyle\bigplus$}
\end{center}

\[
\sum_{i=1}^m\bigplus_{j=1}^n\dots\bigplus_{k=1}^p x_{ijk}
\]
\begin{center}% to test text style
$\sum_{i=1}^m\bigplus_{j=1}^n\dots\bigplus_{k=1}^p x_{ijk}$
\end{center}

\LARGE % test for sizes
\[
\sum_{i=1}^m\bigplus_{j=1}^n\dots\bigplus_{k=1}^p x_{ijk}
\]
\begin{center}% to test text style
$\sum_{i=1}^m\bigplus_{j=1}^n\dots\bigplus_{k=1}^p x_{ijk}$
\end{center}

\end{document}

Question 2

我的答案如下：大运营商是如何定义的？. 提供了两个完全独立的宏（\foo和\barr），取决于是否希望\displaystyle版本变大或保持与相同的大小\textstyle。

\documentclass{article}
\usepackage{amsmath}
\DeclareMathOperator*{\foo}{\scalerel*{+}{\sum}}
\DeclareMathOperator*{\barr}{\scalerel*{+}{\textstyle\sum}}
\usepackage{scalerel}

\begin{document}
\[
\foo_{i=3}^{6}(f^2(i))
\]

This is inline: \(\foo_{i=3}^{6}(f^2(i)) \)

\[
\barr_{i=3}^{6}(f^2(i))
\]

This is inline: \(\barr_{i=3}^{6}(f^2(i)) \)
\end{document}

Answer

我的答案如下：大运营商是如何定义的？. 提供了两个完全独立的宏（\foo和\barr），取决于是否希望\displaystyle版本变大或保持与相同的大小\textstyle。

\documentclass{article}
\usepackage{amsmath}
\DeclareMathOperator*{\foo}{\scalerel*{+}{\sum}}
\DeclareMathOperator*{\barr}{\scalerel*{+}{\textstyle\sum}}
\usepackage{scalerel}

\begin{document}
\[
\foo_{i=3}^{6}(f^2(i))
\]

This is inline: \(\foo_{i=3}^{6}(f^2(i)) \)

\[
\barr_{i=3}^{6}(f^2(i))
\]

This is inline: \(\barr_{i=3}^{6}(f^2(i)) \)
\end{document}

Question 3

如果不采取适当的初步措施，您无法将 LaTeX3 代码复制到序言中。下面我将展示如何通过 LaTeX2e 代码实现相同的想法。此解决方案还支持amsmath与点和 [ no]sumlimits选项相关的标准行为：

% My standard header for TeX.SX answers:
\documentclass[a4paper]{article} % To avoid confusion, let us explicitly 
                                 % declare the paper format.

\usepackage[T1]{fontenc}         % Not always necessary, but recommended.
% End of standard header.  What follows pertains to the problem at hand.

\usepackage{amsmath}

\makeatletter

\newcommand*\@bigplus[1]{\vcenter{\hbox{#1$\m@th +$}}}
\newcommand*\bigplus{%
    \DOTSB % omit this line if you are not using the amsmath package
    \mathop{%
        \mathchoice
            {\@bigplus \huge}%
            {\@bigplus \LARGE}%
            {\@bigplus {}}%
            {\@bigplus \footnotesize}%
    }%
    \slimits@ % omit this line if you are not using the amsmath package
}

\makeatother



\begin{document}

In-line: \( \bigplus_{i=3}^{6} f^2(i) \).
Displayed: \[ \bigplus_{i=3}^{6} f^2(i) \]
Behavior with dots:
\[
    \bigplus_{i_{1}=0}^{n_{1}}\dots\bigplus_{i_{k}=0}^{n_{k}}
        f(i_{1},\dots,i_{k})
\]

\end{document}

这是输出：

添加

正如@egreg指出的那样他的评论，上述答案（然而，它只是模仿了该mathtools包的功能\bigtimes）是有缺陷的。正确的解决方案是使用mathabx包，与问题中所述相反，它确实提供了\bigplus“大运算符”。此解决方案使用专门为此目的设计的字体绘制的字符，因此不依赖于graphics/graphicx包提供的扩展；特别是，它也适用于 DVI 输出（就这一点而言）。

如果您不喜欢该mathabx软件包对数学符号所做的更改，您可以随时自行加载适当的字体并仅定义您感兴趣的命令。以下示例定义了\bigplus以及\bigtimes。请允许我发表几点评论：

amsmath如果加载了该包，代码将支持有关点和“限制”的包的功能；
与mathabx软件包本身的做法相反，mathx 字体系列的定义方式是为了利用当今发行版中安装的较小字体大小。

后一种设计可以改善小于 10 点的尺寸的输出，使其看起来比使用graphics缩放的解决方案更好。

以下是代码：

% My standard header for TeX.SX answers:
\documentclass[a4paper]{article} % To avoid confusion, let us explicitly 
                                 % declare the paper format.

\usepackage[T1]{fontenc}         % Not always necessary, but recommended.
% End of standard header.  What follows pertains to the problem at hand.

\usepackage{amsmath} % comment out to see changes

\DeclareFontFamily{U}{mathx}{\hyphenchar\font45}
\DeclareFontShape{U}{mathx}{m}{n}{
    <5> <6> <7> <8> <9> <10> gen * mathx
    <10.95> mathx10
    <12> <14.4> <17.28> <20.74> <24.88> mathx12
}{}
\DeclareFontSubstitution{U}{mathx}{m}{n}
\DeclareSymbolFont{mathx}{U}{mathx}{m}{n}
\DeclareMathSymbol{\bigplus} {\mathop}{mathx}{"90}
\DeclareMathSymbol{\bigtimes}{\mathop}{mathx}{"91}

\makeatletter

\@ifpackageloaded{amsmath}{%
    \@ifundefined{coprod@}{}{
        \typeout{*** Applying amsmath patches to \protect\bigplus\space
                    and \protect\bigtimes. ***}
        \global\let\bigplus@\bigplus
        \gdef\bigplus{\DOTSB\bigplus@\slimits@}
        \global\let\bigtimes@\bigtimes
        \gdef\bigtimes{\DOTSB\bigtimes@\slimits@}
    }
}{}

\makeatother



\begin{document}

In-line: \( \bigplus_{i=3}^{6} f^2(i) \).
Displayed: \[ \bigplus_{i=3}^{6} f^2(i) \]
Behavior with dots:
\[
    \bigplus_{i_{1}=0}^{n_{1}}\dots\bigplus_{i_{k}=0}^{n_{k}}
        f(i_{1},\dots,i_{k})
\]

In-line: \( \bigtimes_{i=3}^{6} f^2(i) \).
Displayed: \[ \bigtimes_{i=3}^{6} f^2(i) \]
Behavior with dots:
\[
    \bigtimes_{i_{1}=0}^{n_{1}}\dots\bigtimes_{i_{k}=0}^{n_{k}}
        f(i_{1},\dots,i_{k})
\]

Now it works in footnotes too.\footnote{As this example shows.
In-line: \( \bigplus_{i=0}^{n} f(i) \), \( \bigtimes_{i=0}^{n} f(i) \).
Displayed: \[ \bigplus_{i=0}^{n} f(i) \ne \bigtimes_{i=0}^{n} f(i) \]
That's good!}

\LARGE
\verb|\LARGE| text.
In-line: \( \bigtimes_{i=3}^{6} f^2(i) \).
Displayed: \[ \bigtimes_{i=3}^{6} f^2(i) \]
Behavior with dots:
\[
    \bigtimes_{i_{1}=0}^{n_{1}}\dots\bigtimes_{i_{k}=0}^{n_{k}}
        f(i_{1},\dots,i_{k})
\]

\end{document}

它的输出如下：

Answer