Problems with amsmath and Minion and TexLive 2020

Question

The following file, a very much shortened version of my 2000 page free physics textbook, does not compile properly:

\documentclass{book}

\usepackage[fullfamily,textlf, opticals, swash, onlytext]{MinionPro}
\usepackage[extraops,textcomp,withamsmath,amssymb]{minionmath}

\makeatletter
\let\arc\@undefined % else conflict with ``curves.sty''
\DeclareMathAccent{\arcacc}           {\mathord}  {letters}  {5}
\makeatother

\usepackage{amsmath}            % allows {align} 
\usepackage{minionamsmath}
\usepackage{curves,calc}           
\usepackage{bm}                 % makes bold math possible using \bm{...}

\begin{document}
\begin{equation}
    m{\bm{\ddot x}}= q {\bm E} + q {\bm {\dot x}} \times {\bm B} 
\end{equation}
\end{document}

On my TexLive 2020 system, (latex with the dvi - ps - pdf route, thus I use: latex test; dvips test; and then Distiller) ((I do not use pdflatex; my mistake)) the commands \ddot and \dot behave wrongly (they behaved correctly with TexLive 2017); they do not produce dots, but strange signs across the bold x. The culprit is amsmath; if I take it out (ignoring the error), the equation is typeset correctly. But with it, something goes wrong. (And I do need amsmath ...)

Does this happen on all systems? What can be done?

P.S. xelatex makes the same mistake. So does pdflatex. This is some package incompatibility.

P.P.S. I used tracingmacros=1 with and without amsmath and compared the 2 files. The latex code was just this, even simpler equation:

\begin{equation}
    m{\boldsymbol{\ddot x}}
\end{equation}

The main difference (of the two 400kByte log files) is probably this part:

9113c9178
< \ddot ->\protect \mathaccentV {ddot}104
---
> \ddot ->\protect \ddot  
9116a9182,9183
> \ddot  ->\mathaccentV {ddot}07F
> 
9216c9283
< \bm@command ->\mathaccent 30724 
---
> \bm@command ->\mathaccent 30591 
9252c9319
< \bm@command ->\mathaccent 30724 \mathchar 31096 
---
> \bm@command ->\mathaccent 30591 \mathchar 31096 

It seems that \ddot is mapped to different mathaccents in the two cases...

P.P.P.S. I have several hundred eps figures, use psfrag and use raw postscript code. I also use the wonderful MinionMath fonts, the microtype package with many details, and a 5000 line long cls file. It seems that the latex command is getting outdated. Should I switch to XeLateX? Or to Luatex? I would be interested in hearing the thoughts and advice of the Pros...

Answer 1

The problem affects all "standard math accents":

\hat \check \tilde \acute \grave \dot \ddot \breve \bar \vec

The problem is due to a changed macro in amsmath.sty.

amsmath.sty 2017/09/02 v2.17a had in line 725:

\def\@tempa#1{\@xp\@tempb\meaning#1\@nil#1}

amsmath.sty 2020/01/20 v2.17e now has in lines 747 to 753:

\def\@tempa#1{%   
  \@ifundefined{\@xp\@gobble\string#1\space}%
     {\@xp\@tempb\meaning#1\@nil#1}%
     {\@xp\@xp\@xp\@tempb\@xp\meaning
       \csname\@xp\@gobble\string#1\space\endcsname\@nil#1}% }

With this changed definition, the accents from Minion Math do not work any more.

A simple way to get rid of this problem would be to take the lines with \DeclareMathAccent from the file fontmath.minion (supplied with the LaTeX support of Minion Math) and to put these in the preamble after amsmath.sty, e.g.

\DeclareMathAccent{\hat}              {\mathalpha}{letters}  {2}
\DeclareMathAccent{\ddot}             {\mathalpha}{letters}  {4}
\DeclareMathAccent{\dot}              {\mathalpha}{letters} {10}
\DeclareMathAccent{\dddot}            {\mathord}  {letters} {11}
\DeclareMathAccent{\ddddot}           {\mathord}  {letters} {12}

This could be included in the LaTeX support, in files minion.sty and minionamsmath.sty, and I will do so when I update the support files.

Some additional remarks:

I also do strongly recommend to use unicode-math and LuaLaTeX or XeLaTeX whenever possible. All issues with fonts and encodings are much easier to handle, it does not need all the support files, and all glyphs in the fonts could be accessed in an easy way. I do supply the LaTeX support for Minion Math mainly for legacy documents.

The LaTeX support for Minion Math used "newmath" encodings as default, with 256 slots per encoding. This conflicts with amsmath at some points (e.g. amsmath "synthesizes" some glyphs from components – multiple integral signs, dddot and ddddot accents, etc. – while these are "real glyphs" in Minion Math).

Therefore minionmath.sty, the main package of the LaTeX support, has an option "withamsmath", which simply undefines conflicting commands. And there's a second small package minionamsmath.sty, with the sole task of redefining these commands, after amsmath is loaded.

With current amsmath, it seems accents should be added to "undefined commands" in minionmath.sty and to "redefined commands" in minionamsmath.sty.

So the load order of packages (as in the original question) is correct and intentional:

• minionmath (with option "withamsmath")

• amsmath

• minionamsmath

"newmath" was a TeX project with the aim to define new encoding standard for TeX math fonts, similar to "ec" for text fonts, but it was abandoned in favour of Unicode math and never became a standard. Still I used it as a starting point for Minion Math.

Besides, in my view, the accents in the original question should not be bold:

\begin{equation}
    m\ddot{\bm{x}}= q {\bm E} + q \dot{\bm{x}} \times {\bm B} 
\end{equation}

Answer 2

Davislor put me on the right track. Here is a partial solution.

The following file compiles correctly with latex-dvip-Distiller, with pdflatex and with xelatex. I moved the loading of amsmath upwards, and I added two definitions for \iint and \iiint.

---

\documentclass{book}    
\usepackage{amsmath}           
\usepackage[fullfamily,textlf, opticals, swash, onlytext]{MinionPro}
\usepackage[extraops,textcomp,withamsmath,amssymb]{minionmath}

\makeatletter
\let\arc\@undefined % else conflict with ``curves.sty''
\DeclareMathAccent{\arcacc}           {\mathord}  {letters}  {5}
\makeatother

\def\iint{\relax}
\def\iiint{\relax}

\usepackage{minionamsmath}
\usepackage{curves,calc}           
\usepackage{bm}                 % makes bold math possible using \bm{...}

\begin{document}
\tracingmacros=1
\begin{equation}
    m{\boldsymbol{\ddot x}}
\end{equation}
\end{document}

Note the strange definitions for \iint and \iint that are necessary, because incompatibilities are still present. Also the full 2000 page book appears to typeset correctly again.

Here is a general comment about Latex. My 5000 line cls file has surely more than 1000 lines of code like

\makeatletter
\let\arc\@undefined % else conflict with ``curves.sty''
\DeclareMathAccent{\arcacc}           {\mathord}  {letters}  {5}
\makeatother

\def\iint{\relax}
\def\iiint{\relax}

Lines such as these are only needed to avoid clashes/incompatibilities between packages. (Around 60 packages are used in the free physics book.) In an ideal world, such code lines would not be necessary...