Support `*smallmatrix` and `align` key in the `diagmat` module

[myhsia]

The mathtools package has all kinds of matrices with a small appearance, and setting the align of every matrix element is supported.

It seems that many *.dtx files for modules have disappeared in this repo. So I open an issue instead of a PR.

I downloaded the phy-diagmat.sty on CTAN and then modified it, and the modified code is attached at the end.

• demo

\documentclass{article}

\usepackage{physics2, mathtools}
\usephysicsmodule{diagmat}

\begin{document}

The normal ones:
\[
  \begin{array}{lll}
    \diagmat{-1, 2, 123}  & \pdiagmat{-1, 2, 123} & \bdiagmat{-1, 2, 123}\\[1em]
    \Bdiagmat{-1, 2, 123} & \vdiagmat{-1, 2, 123} & \Vdiagmat{-1, 2, 123}
  \end{array}
\]

The small ones:
\[
  \begin{array}{lll}
    \diagmat*{-1, 2, 123}  & \pdiagmat*{-1, 2, 123} & \bdiagmat*{-1, 2, 123}\\[1em]
    \Bdiagmat*{-1, 2, 123} & \vdiagmat*{-1, 2, 123} & \Vdiagmat*{-1, 2, 123}
  \end{array}
\]

And configure the align:
\[
  \begin{array}{lll}
    \diagmat[empty = {a}, align = r]{-1, 2, 123} &
    \pdiagmat[empty = {}, align = c]{-1, 2, 123} &
    \bdiagmat[empty = {}, align = l]{-1, 2, 123} \\[1em]
    \Bdiagmat[align = l]{-1, 2, 123} &
    \vdiagmat[align = c]{-1, 2, 123} &
    \Vdiagmat[align = r]{-1, 2, 123}
  \end{array}
\]
\end{document}

• modified .sty file

%%
%% This is file `phy-diagmat.sty',
%% generated with the docstrip utility.
%%
%% The original source files were:
%%
%% physics2-code.dtx  (with options: `diagmat')
%% 
%%   Copyright (C) 2023 by Zhang Tingxuan <alphaztx@163.com>
%% 
%%   This work may be distributed and/or modified under the
%%   conditions of the LaTeX Project Public License, either
%%   version 1.3c of this license or (at your option) any later
%%   version. The latest version of this license is in:
%% 
%%     http://www.latex-project.org/lppl.txt
%% 
%%   and version 1.3 or later is part of all distributions of
%%   LaTeX version 2005/12/01 or later.
%% 
%%   This work has the LPPL maintenance status `maintained'.
%% 
%%   The Current Maintainer of this work is Zhang Tingxuan.
%% 
%%   This work consists of the files physics2-code.dtx,
%%             and the derived files physics2.ins,
%%                                   physics2.sty,
%%                                   phy-<module>.sty,
%%                                   physics2-code.pdf,
%%                               and README.md.
%% 
\ProvidesExplFile{phy-diagmat.sty}{2025/10/30}{}
  {`diagmat' module of physics2}
\RequirePackage { amsmath }
\phy@define@key { diagmat } { empty } [ 0 ] { \tl_gset:Nn \l__phy_mat_empty_tl { #1 } }
\clist_new:N \l__phy_mat_diag_clist
\int_new:N \l__phy_mat_dim_int
\tl_new:N \l__phy_mat_line_tl
\tl_new:N \l__phy_diagmat_tl
\tl_new:N \l__phy_mat_empty_tl
\tl_new:N \l__phy_mat_align_tl
\phy@processkeyopt { diagmat }
\keys_define:nn { phy/diagmat }
  {
    empty   .tl_set:N   = \l__phy_mat_empty_tl,
      empty .initial:n  = 0,
    align .tl_set:N     = \l__phy_mat_align_tl,
  }
\DeclareDocumentCommand \diagmat { s O{} m }
  {
    \IfBooleanTF {#1}
      { \__phy_diagmat_type:nnn {  small } {#2} {#3} }
      { \__phy_diagmat_type:nnn {        } {#2} {#3} }
  }
\DeclareDocumentCommand \pdiagmat { s O{} m }
  {
    \IfBooleanTF {#1}
      { \__phy_diagmat_type:nnn { psmall } {#2} {#3} }
      { \__phy_diagmat_type:nnn { p      } {#2} {#3} }
  }
\DeclareDocumentCommand \bdiagmat { s O{} m }
  {
    \IfBooleanTF {#1}
      { \__phy_diagmat_type:nnn { bsmall } {#2} {#3} }
      { \__phy_diagmat_type:nnn { b      } {#2} {#3} }
  }
\DeclareDocumentCommand \Bdiagmat { s O{} m }
  {
    \IfBooleanTF {#1}
      { \__phy_diagmat_type:nnn { Bsmall } {#2} {#3} }
      { \__phy_diagmat_type:nnn { B      } {#2} {#3} }
  }
\DeclareDocumentCommand \vdiagmat { s O{} m }
  {
    \IfBooleanTF {#1}
      { \__phy_diagmat_type:nnn { vsmall } {#2} {#3} }
      { \__phy_diagmat_type:nnn { v      } {#2} {#3} }
  }
\DeclareDocumentCommand \Vdiagmat { s O{} m }
  {
    \IfBooleanTF {#1}
      { \__phy_diagmat_type:nnn { Vsmall } {#2} {#3} }
      { \__phy_diagmat_type:nnn { V      } {#2} {#3} }
  }
\cs_new:Npn \__phy_diagmat_type:nnn #1#2#3
  {
    \group_begin:
    \clist_set:Nn \l__phy_mat_diag_clist { #3 }
    \int_set:Nn \l__phy_mat_dim_int { \clist_count:N \l__phy_mat_diag_clist }
    \int_compare:nNnT { \l__phy_mat_dim_int } > { \value { MaxMatrixCols } }
      { \setcounter { MaxMatrixCols } { \l__phy_mat_dim_int } }
    \keys_set:nn { phy/diagmat } { #2 }
    \tl_gclear:N \l__phy_diagmat_tl
    \int_step_inline:nnn { 1 } { \l__phy_mat_dim_int }
      {
        \int_step_inline:nnn { 1 } { \l__phy_mat_dim_int }
          {
            \int_compare:nNnTF { ##1 } = { ####1 }
              {
                \clist_gpop:NN \l__phy_mat_diag_clist \l__phy_tmpa_tl
                \tl_if_empty:NTF \l__phy_tmpa_tl
                  { \tl_gput_right:Nn \l__phy_mat_line_tl { \l__phy_mat_empty_tl } }
                  { \tl_gput_right:No \l__phy_mat_line_tl { \l__phy_tmpa_tl } }
              }
              { \tl_gput_right:Nn \l__phy_mat_line_tl { \l__phy_mat_empty_tl } }
            \int_compare:nNnTF { ####1 } = { \l__phy_mat_dim_int }
              {
                \tl_gput_right:Nn \l__phy_mat_line_tl { \\ }
              }
              {
                \tl_gput_right:Nn \l__phy_mat_line_tl { & }
              }
          }
        \tl_gput_right:No \l__phy_diagmat_tl { \l__phy_mat_line_tl }
        \tl_gclear:N \l__phy_mat_line_tl
      }
    \tl_if_empty:NTF { \l__phy_mat_align_tl }
      {
        \begin { #1 matrix }
          \tl_use:N \l__phy_diagmat_tl
        \end { #1 matrix }
      }
      {
        \begin { #1 matrix* } [ \l__phy_mat_align_tl ]
          \tl_use:N \l__phy_diagmat_tl
        \end { #1 matrix* }
      }
    \group_end:
  }
\endinput
%%
%% End of file `phy-diagmat.sty'.

[AlphaZTX]

我会考虑加进去，下个版本再说