我注意到讲师在他的笔记中使用了不同的和符号，但对我来说，通用字体似乎是标准字体。
我怎样才能使用这样的求和符号？
答案1
更新 1：2024/05/03
该\sum符号取自包装txfonts（或者您可以从中取出Libertinus Math）：参见图中的简短 MWE 和。
%% Compile and read me!
\documentclass[a4paper,12pt]{article}
\usepackage{txfonts}
\usepackage[T1]{fontenc}
\begin{document}
\[\sum^{n}_{i=1}{xcv}\]
\end{document}
使用引擎XeLaTeX：在我看来，非常接近的\sum符号来自STIX 两个数学。我也试过了Cambria Math（见第二个代码），但它太大了：但是可以用scalerel包垂直拉伸符号（我没有试过）。如果你知道常用字体，你可以取消STIX Two Math并输入字体名称。
\documentclass[12pt]{article}
\usepackage{unicode-math}
\setmathfont{Latin Modern Math}
\setmathfont[range={\sum}, Scale=MatchUppercase]{STIX Two Math}
\let\mathbb\relax % remove the definition by unicode-math
\DeclareMathAlphabet{\mathbb}{U}{msb}{m}{n}
\begin{document}
The range of matrix $A\in\mathbb{K}^{I\times J}$ is
\[
\operatorname{range}(A)=\{Ax\colon x\in\mathbb{K}^{J}\}=\operatorname{span}\{A_{(j)},i\in J\}.
\]
Hence, the range of a matrix is a vector space spanned by its columns. The Euclidean scalar product in $\mathbb{K}^I$ is given by.
\[\langle x,y\rangle=y^Hx=\sum_{i\in I}x_i\bar{y}_i,\]
where for $\mathbb{K}=\mathbb{R}$ the conjugate sign can be ignored. It is often useful and very
\end{document}
或者使用 Cambria Math：
\documentclass[12pt]{article}
\usepackage{unicode-math}
\setmathfont{Latin Modern Math}
\setmathfont[range={\sum}, Scale=MatchUppercase]{Cambria Math}
\let\mathbb\relax % remove the definition by unicode-math
\DeclareMathAlphabet{\mathbb}{U}{msb}{m}{n}
\begin{document}
The range of matrix $A\in\mathbb{K}^{I\times J}$ is
\[
\operatorname{range}(A)=\{Ax\colon x\in\mathbb{K}^{J}\}=\operatorname{span}\{A_{(j)},i\in J\}.
\]
Hence, the range of a matrix is a vector space spanned by its columns. The Euclidean scalar product in $\mathbb{K}^I$ is given by.
\[\langle x,y\rangle=y^Hx=\sum_{i\in I}x_i\bar{y}_i,\]
where for $\mathbb{K}=\mathbb{R}$ the conjugate sign can be ignored. It is often useful and very
\end{document}
您还可以看到这个TeX Gyre Pagella Math（好的）：
\documentclass[12pt]{article}
\usepackage{unicode-math}
\setmathfont{Latin Modern Math}
\setmathfont[range={\sum}, Scale=MatchUppercase]{TeX Gyre Pagella Math}
\let\mathbb\relax % remove the definition by unicode-math
\DeclareMathAlphabet{\mathbb}{U}{msb}{m}{n}
\begin{document}
The range of matrix $A\in\mathbb{K}^{I\times J}$ is
\[
\operatorname{range}(A)=\{Ax\colon x\in\mathbb{K}^{J}\}=\operatorname{span}\{A_{(j)},i\in J\}.
\]
Hence, the range of a matrix is a vector space spanned by its colunns. The Euclidean scalar product in $\mathbb{K}^I$ is given by.
\[\langle x,y\rangle=y^Hx=\sum_{i\in I}x_i\bar{y}_i,\]
where for $\mathbb{K}=\mathbb{R}$ the conjugate sign can be ignored. It is often useful and very
\end{document}
有TeX Gyre Termes Math良好的）：
