Why "p" in pmatrix?

Question

I am using the command \begin{pmatrix} [...] \end{pmatrix}. I wonder why this command is not just called \begin{matrix} [...] \end{matrix} and why a "p" before "matrix".

"p" for "parenthesis", the surrounding delimiter. One might surmise that bmatrix is for bracketed matrices. — Steven B. Segletes, Jan 19 '16 at 15:16
The matrix environment is the generic version -- it has no delimiters. — , Jan 19 '16 at 15:18
And B for “braces”, v for “vert” (like in \vert), V for “Vert” (like in \Vert). — egreg, Jan 19 '16 at 15:19
@StevenB.Segletes: You were the first who commented -- would you write the answer as an anthology on matrix delimiters? ;-) — , Jan 19 '16 at 15:37
@ChristianHupfer You can do it also! (if Steven does not do it) — Colas, Jan 19 '16 at 15:55
@Colas: Only if Steven doesn't write it -- 'grace period' -- I am waiting — , Jan 19 '16 at 16:00

score 33 · Accepted Answer · answered Jan 19 '16 at 17:21

The amsmath package provides a number of options. The leading letter before matrix indicates the delimiter that is used:

p for parens, b for brackets, v for verts, B for braces, V for double verts.

\documentclass{article}
\usepackage{amsmath,tabstackengine}
\begin{document}
\[
\begin{matrix}
1&2&3\\
4&5&6\\
7&8&9
\end{matrix}
\quad
\begin{pmatrix}
1&2&3\\
4&5&6\\
7&8&9
\end{pmatrix}
\quad
\begin{bmatrix}
1&2&3\\
4&5&6\\
7&8&9
\end{bmatrix}
\quad
\begin{vmatrix}
1&2&3\\
4&5&6\\
7&8&9
\end{vmatrix}
\]
\[
\begin{Bmatrix}
1&2&3\\
4&5&6\\
7&8&9
\end{Bmatrix}
\quad
\begin{Vmatrix}
1&2&3\\
4&5&6\\
7&8&9
\end{Vmatrix}
\]
\end{document}

score 2 · Answer 2 · answered Sep 23 '22 at 06:11

2

Plain TeX defines the macro \pmatrix as matrix with parentheses and \matrix as the same without parentheses. So, the terminology mentioned here is inspired by plain TeX.

answered Sep 23 '22 at 06:11

wipet

74,238

score -1 · Answer 3 · answered Sep 23 '22 at 02:09

-1

The "p" in pmatrix stands for "parentheses"

There is also Bmatrix for "Brace Matrix"

and... bmatrix for "bracket Matrix"

answered Sep 23 '22 at 02:09

IdleCustard

1,194

6

All this is already mentioned in the @Steven B. Segletes answer, from where is also showed image ... – Zarko Sep 23 '22 at 02:17

Why "p" in pmatrix?

3 Answers3