How to create a Matrix with Label on its top?

Question

I've been trying to create a matrix (displayed in the image below), and I haven't been able to figure out so far.

I've tried the following code (as an example), but its not quite the same as you can see in the image. Can someone please guide me about this?

\documentclass{article}
\usepackage[utf8]{inputenc}
\usepackage{blkarray}
\begin{document}
[
\begin{blockarray}{ccccc}
a & b & c & d & e \
\begin{block}{(ccccc)}
  1 & 1 & 1 & 1 & 1   \
  0 & 1 & 0 & 0 & 1   \
  0 & 0 & 1 & 0 & 1   \
  0 & 0 & 0 & 1 & 1   \
  0 & 0 & 0 & 0 & 1   \
\end{block}
\end{blockarray}
 ]
\end{document}

Please tell us what, specifically, you're trying to change. E.g., would you like square brackets instead of round parentheses? Colums or rows of \dots? The math font? — Mico, Feb 04 '21 at 05:17
@Mico I'd like to reproduce the exact matrix as shown in figure. So far, I've been unable to create square brackets, T_i and dots. Some guidance would be much appreciated. — Anees, Feb 04 '21 at 05:49
Does this answer your question? Write elements above and right outside the matrix — José Carlos Santos, Feb 04 '21 at 06:35
Another likely duplicate: \bordermatrix with brackets [ ] instead of parentheses — barbara beeton, Feb 04 '21 at 21:03

score 9 · Accepted Answer · answered Feb 04 '21 at 06:25

With {bNiceMatrix} of nicematrix:

\documentclass{article}
\usepackage{nicematrix}
\begin{document}
[T_i = 
\begin{bNiceMatrix}[first-row]
W_1 & W_2 & W_3 & \cdots & W_m \ 
e_{11} & e_{22} & e_{31} & \cdots & e_{m1} \
e_{12} & e_{22} & e_{32} & \cdots & e_{m2} \
e_{13} & e_{23} & e_{33} & \cdots & e_{m3} \
\vdots & \cdots & \cdots & \cdots & \vdots \
e_{1K} & e_{2K} & e_{3K} & \cdots & e_{mK} \
\end{bNiceMatrix}
]
\end{document}

score 8 · Answer 2 · answered Feb 04 '21 at 08:19

There is \bordermatrix macro in plain TeX:

$$
  \delcode`(=\delcode`[  \delcode`)=\delcode`]
  T_i =
  \bordermatrix{ & W_1    & W_2    & W_3    & \cdots & W_m    \cr
                 & e_{11} & e_{21} & e_{31} & \cdots & e_{m1} \cr 
                 & e_{12} & e_{22} & e_{32} & \cdots & e_{m2} \cr 
                 & e_{13} & e_{23} & e_{33} & \cdots & e_{m3} \cr 
                 & \vdots & \cdots & \cdots & \cdots & \vdots \cr
                 & e_{13} & e_{23} & e_{33} & \cdots & e_{m3} \cr }
$$
\bye

score 4 · Answer 3 · answered Feb 04 '21 at 10:25

You are almost done, you only need to change tip of brackets in block and replace matrix elements, where you like to have dots with \cdots for horizontal dots and \vdots for vertical:

\documentclass{article}
\usepackage{blkarray}
\begin{document}
[T_i =
\begin{blockarray}{ccccc}
W_1 & W_2 & W_3 & \cdots & W_m \
\begin{block}{[ccccc]}  % <--- observe [ and ] 
e_{11} & e_{22} & e_{31} & \cdots & e_{m1} \
e_{12} & e_{22} & e_{32} & \cdots & e_{m2} \
e_{13} & e_{23} & e_{33} & \cdots & e_{m3} \
\vdots & \cdots & \cdots & \cdots & \vdots \ % <--- observe dots
e_{1K} & e_{2K} & e_{3K} & \cdots & e_{mK} \ % <--- observe dots
\end{block}
\end{blockarray}
]
\end{document}

Code is simple and for final result need only one compilations.

How to create a Matrix with Label on its top?

3 Answers3