Prevent fontsize command resize equation numbers

Question

I'm copy-editing a paper where the author used \fontsize to resize equations:

\documentclass[11pt]{article}
\usepackage{amsmath}
\pagestyle{empty}
\begin{document}
Normal size equation and equation number:
\begin{equation}
x+y=z
\end{equation}
Resized size equation and equation numbers
{\fontsize{8pt}{0}
\begin{align}
\widehat{P}1 & = 3 {\left(N + 3\right)} {\left(N + 2\right)} {\left(N + 1\right)}^{2} N^{2} {\left(N - 1\right)} {\left(N - 2\right)} {\left(N - 3\right)} Q{mult} Q_{1} \label{EQ1}\
\widehat{P}2 & = 3 {\left(N + 1\right)} N^{2} {\left(N - 1\right)} {\left(N - 2\right)} {\left(N - 3\right)} Q{mult} Q_{2}
\label{EQ2}\end{align}}
\end{document}

In the most cases the resizing is acceptable (ugly but acceptable) but I need the equation numbers not be resized. Can I get the equation numbers to not be resized?

@UlrikeFischer thanks, I think this question should be marked as a duplicate. I'd prefer not delete it. — Gabriele, Feb 28 '21 at 19:34

egreg · Answer 1 · 2021-03-01T08:01:51.997

I'm not sure this is typographically sound.

\documentclass{article}
\usepackage{amsmath}
\usepackage{xpatch}
\makeatletter
\let\nicolardi@align@preamble\align@preamble
\xpatchcmd{\nicolardi@align@preamble}
  {&\hfil}
  {&\nicolardi@size\hfil}
  {}{}
\xpatchcmd{\nicolardi@align@preamble}
  {&\setboxz@h}
  {&\nicolardi@size\setboxz@h}
  {}{}
\newenvironment{sizedalign}[1]
  {\def\nicolardi@size{#1}\let\align@preamble\nicolardi@align@preamble\align}
  {\endalign}
\makeatother
\begin{document}
\begin{align}
a &= b \
c &= ddddddddd
\end{align}
\begin{sizedalign}{\footnotesize}
a &= b \
c &= ddddddddd
\end{sizedalign}
\end{document}

Here's your example, with the needed corrections: I removed all \left and \right commands and the useless braces; moreover, the mult subscript requires \mathrm.

\begin{sizedalign}{\footnotesize}
\widehat{P}_1 & = 3(N+3)(N+2)(N+1)^{2}N^{2}(N-1)(N-2)(N-3)Q_{\mathrm{mult}}Q_{1}
\label{EQ1}\\
\widehat{P}_2 & = 3(N+1)N^{2}(N-1)(N-2)(N-3)Q_{\mathrm{mult}} Q_{2}
\label{EQ2}
\end{sizedalign}

Explanation. The align environment uses \halign with a suitable preamble that's stored in \align@preamble which defines repeatable pairs of columns. The macro is copied and the copy is patched to add at the beginning of every cell the size declaration given as argument to sizedalign. This new environment locally redefines \align@preamble to the patched copy, then calls \align to do the work.

I didn't understand what you mean with "no useless braces and \mathrm for the subscript". In the example you are using \mathrm for the subscript. Anyway I don't need the subscripts to be always in roman. — Gabriele, Feb 28 '21 at 23:33
Ah, ok! Thanks! I know that mult subscript requires \mathrm. I would have fixed it later. But thank you for pointing it. — Gabriele, Mar 01 '21 at 19:45

score 2 · Answer 2 · edited Feb 28 '21 at 22:53

I propose a variant solution with the medmath command from nccmath, which reduces the size of math formulæ by about 20 % (so the result will not be exactly 8 pt, but not very different):

    \documentclass[11pt]{article}
    \usepackage{amsmath, nccmath}
    \pagestyle{empty}
\begin{document}

Resized size equation and equation numbers
{\fontsize{8pt}{0}
\begin{align}
\widehat{P}_1 &amp; = 3 {\left(N + 3\right)} {\left(N + 2\right)} {\left(N + 1\right)}^{2} N^{2} {\left(N - 1\right)} {\left(N - 2\right)} {\left(N - 3\right)} Q_\text{mult} Q_{1} \label{EQ1}\\
\widehat{P}_2 &amp; = 3 {\left(N + 1\right)} N^{2} {\left(N - 1\right)} {\left(N - 2\right)} {\left(N - 3\right)} Q_\text{mult} Q_{2}
\label{EQ2}\end{align}}

With the medmath command:
\begin{align}
\medmath{\widehat{P}_1} &amp; = \medmath{3 {\left(N + 3\right)} {\left(N + 2\right)} {\left(N + 1\right)}^{2} N^{2} {\left(N - 1\right)} {\left(N - 2\right)} {\left(N - 3\right)} Q_\text{mult} Q_{1} }\label{EQ1}\\
\medmath{\widehat{P}_2 }&amp; = \medmath{3 {\left(N + 1\right)} N^{2} {\left(N - 1\right)} {\left(N - 2\right)} {\left(N - 3\right)} Q_\text{mult} Q_{2}}
\label{EQ2}
\end{align}

Normal size:
\begin{align}
\widehat{P}_1 &amp; = 3 {\left(N + 3\right)} {\left(N + 2\right)} {\left(N + 1\right)}^{2} N^{2} {\left(N - 1\right)} {\left(N - 2\right)} {\left(N - 3\right)} Q_\text{mult} Q_{1} \label{EQ1}\\
\widehat{P}_2 &amp; = 3 {\left(N + 1\right)} N^{2} {\left(N - 1\right)} {\left(N - 2\right)} {\left(N - 3\right)} Q_\text{mult} Q_{2}
\label{EQ2}

\end{align}
\end{document}

Sorry, it seems I had a copy-paste accident. I'l fix that instantly. Thanks! — Bernard, Feb 28 '21 at 20:15
Thanks for your \medmath solution but, in my case, it requires to much work. — Gabriele, Feb 28 '21 at 20:33
I also tried the medsize environment, but unfortunately it does not seem to be compatible with align (don't know whether it is due to the & or the \\\ ). — Bernard, Feb 28 '21 at 20:40

score 0 · Accepted Answer · answered Mar 01 '21 at 23:22

As Ulrike Fischer suggested in the comments I solved with:

\makeatletter
  \def\my@tag@font{\normalsize}
  \def\maketag@@@#1{\hbox{\m@th\normalfont\my@tag@font#1}}
  \let\amsmath@eqref\eqref
  \renewcommand\eqref[1]{{\let\my@tag@font\relax\amsmath@eqref{#1}}}
\makeatother

provided here: https://tex.stackexchange.com/a/100148/33634

I learned a lot also from egreg and Bernard answers.

Prevent fontsize command resize equation numbers

3 Answers3