使用 mathastext-package 识别 \mathrm 的智能希腊字母

Question

在我的初始回答中，我甚至没有检查@wipet\setsmartgreek代码。我最初的回答建议使用defaultrm选项，mathastext因为这可以防止包修改与之一起\mathrm工作的字体。但在评论中，有人报告说这取消了太多的mathastext影响。所以我检查了\setsmartgreek的代码，也许只需要使用这个修改后的版本：

% substitute letters and numbers with text font in math mode
\usepackage{mathastext}

% set smart greek letters (adapted to mathastext presence; see \ifnum test)
\def\setsmartgreek{%
    \expandafter\ifx\csname muup\endcsname\relax 
    \else \def\stgreekC##1##2;{##2up}\fi
    \expandafter\ifx\csname upmu\endcsname\relax 
    \else \def\stgreekC##1##2;{up##2}\fi
    \ifx\stgreekC\undefined \errmessage{upright greek letters are not available}%
    \else \expandafter\setsmartgreekA \fi
}
\def\setsmartgreekA#1{\ifx#1\relax \else
    \expandafter \let \csname it:\string#1\endcsname = #1%
    \edef#1{\noexpand\ifnum\fam=\symmtoperatorfont
        \expandafter\noexpand\csname\expandafter\stgreekC\string#1;\endcsname
        \noexpand\else \expandafter\noexpand\csname it:\string#1\endcsname
        \noexpand\fi}%
    \expandafter\setsmartgreekA \fi
}

\setsmartgreek\mu\relax

在我使用 OP 的 MWE 进行的测试中，它起作用了。

OP 补充：

上面的答案似乎只适用于投影机-class 被使用。在其他情况下（例如 KOMA-script、文章），它会导致错误，而旧的宏定义不会出现这种错误。对已加载的类进行简单检查可以解决此问题：

\@ifclassloaded{beamer}{
    \def\familyidentifier{\symmtoperatorfont}
    }{
    \def\familyidentifier{0}
}

在宏中，相关行必须更改为：

\edef#1{\noexpand\ifnum\fam=\familyidentifier
        ...
        }%

以前的答案：

将选项传递defaultrm 给mathastext，或者更好的是包罗万象的defaultalphabets。（查看详细信息文档）

\documentclass{beamer}

\usepackage[T1]{fontenc}
\usepackage[utf8]{luainputenc}
\usepackage{microtype}
\usepackage{amsmath}

% Load fonts, sansmathfonts for symbols etc.
\usepackage{sansmathfonts}
\usepackage[default]{opensans}

% Declare greek letters for math
\DeclareFontEncoding{LGR}{}{}
\DeclareSymbolFont{osgreek}{LGR}{fos}{m}{n}
\SetSymbolFont{osgreek}{bold}{LGR}{fos}{bx}{n}
\DeclareSymbolFont{osgreekit}{LGR}{fos}{m}{it}
\SetSymbolFont{osgreekit}{bold}{LGR}{fos}{bx}{it}

\DeclareMathSymbol{\upmu}{\mathord}{osgreek}{`m}
\DeclareMathSymbol{\muup}{\mathord}{osgreek}{`m}
\DeclareMathSymbol{\mu}{\mathord}{osgreekit}{`m}

% set smart greek letters
\def\setsmartgreek{%
    \expandafter\ifx\csname muup\endcsname\relax 
    \else \def\stgreekC##1##2;{##2up}\fi
    \expandafter\ifx\csname upmu\endcsname\relax 
    \else \def\stgreekC##1##2;{up##2}\fi
    \ifx\stgreekC\undefined \errmessage{upright greek letters are not available}%
    \else \expandafter\setsmartgreekA \fi
}
\def\setsmartgreekA#1{\ifx#1\relax \else
    \expandafter \let \csname it:\string#1\endcsname = #1%
    \edef#1{\noexpand\ifnum\fam=0
        \expandafter\noexpand\csname\expandafter\stgreekC\string#1;\endcsname
        \noexpand\else \expandafter\noexpand\csname it:\string#1\endcsname
        \noexpand\fi}%
    \expandafter\setsmartgreekA \fi
}

\setsmartgreek\mu\relax

% substitute letters and numbers with text font in math mode
\usepackage[defaultrm]{mathastext}

% siunitx should keep working
\usepackage{siunitx}
\sisetup{math-micro=\mathrm{\upmu}}
\AtBeginDocument{\sisetup{detect-all}}

\begin{document}

Regular numbers and unit: \SI{42}{\micro\meter}

\textit{Regular numbers and unit: \SI{42}{\micro\meter}}

\textbf{Bold numbers and unit: \SI{42}{\micro\meter}}

\textbf{\textit{Bold italic numbers and unit: \SI{42}{\micro\meter}}}

\[
\int \sum X_\mathrm{\textcolor{red}{\mu\upmu}}\mu\upmu\mathrm{\textcolor{red}{\mu\upmu}}A + 2 = \SI{42}{\micro\meter\ampere\gram}
\]

All \textcolor{red}{red} should be upright. 

\end{document}

确实，mathastext默认情况下不会对希腊字母进行任何更改。但它确实定义了自己的数学字母表版本（以便使用正确的——在它看来！——字体）。

Answer 1