Small descriptions next to matrix

Question

One of my textbooks notates Markov transition matrices this way with 1 and 2 denoting states:

enter image description here

How can I reproduce this matrix in LaTeX?

The kbordermatrix package is not on CTAN, but it can handle this beautifully. See the duplicate link. You can also change the delimiters, as described in the kbordermatrix documentation. — Werner, May 01 '13 at 18:33

score 1 · Accepted Answer · edited Jun 18 '17 at 08:26

1

[EDITED to resolve the equation axis properly]

\documentclass{article}
\usepackage{amsfonts}
\usepackage{scalerel}
\begin{document}
\def\x{\begin{array}{c}x\\x\end{array}}
\(
\let\svarraycolsep\arraycolsep
\renewcommand\arraystretch{1.4}
\arraycolsep 0.4ex
\begin{array}{c}
\\
\mathbb{P}=\quad\\
\\
\end{array}
\begin{array}{c}
 \\
 {\scriptstyle 1}\\
 {\scriptstyle 2}\\
\\
\end{array}
\begin{array}{c}
 \\
 \scalerel*[1.5ex]{(}{\x}\\
\\
\end{array}
\begin{array}{c}
 {\scriptstyle 1}\\
 1-a\\
 b\\
\\
\end{array}
\begin{array}{c}
 {\scriptstyle 2}\\
 a\\
 1-b\\
\\
\end{array}
\begin{array}{c}
 \\
 \scalerel*[1.5ex]{)}{\x}\\
\\
\end{array}
\mathrm{is~the~answer}
\arraycolsep\svarraycolsep
\renewcommand\arraystretch{1.0}
\)
\end{document}

enter image description here

edited Jun 18 '17 at 08:26

David Carlisle

757,742

answered May 01 '13 at 18:50

Steven B. Segletes

237,551

One caveat with this approach is that your math axis is now slightly distorted. Visually you print P= between rows 2 and 3 of the matrix construction. If you add constructions on either side of this it will vertically align with the middle row (row 2), which would make P= seem off-axis. – Werner May 01 '13 at 19:02
@werner. True, but that can be circumvented by adding an extra [null] row each,to the bottom of the P+ as well as the matrix entries. No? – Steven B. Segletes May 01 '13 at 19:04
...which you then have to compensate for regarding content (say, paragraphs) above/below. The space below this construction is then far greater than the space above... – Werner May 01 '13 at 19:31
@Werner: Uncle! – Steven B. Segletes May 01 '13 at 19:55
A long time without up votes!? Strange. +1. – Sigur Apr 03 '14 at 00:51
1

@Sigur Thanks. I hardly even remember this one. Today, I'd be using stacks to tackle it. Maybe next year, I'll ping you on my zero-vote answer from today ;^) Cheers! – Steven B. Segletes Apr 03 '14 at 01:02

Small descriptions next to matrix

1 Answers1