Math & Science ⇒ Horizontal Line across Matrix

[vaibhavtewari]

Hello friends

I am trying to produce a line across a matrix such that it is between rows, but I am not succeeding. Can anyone help, I am attaching my desired output.

thanks

[localghost]

Two possible solutions.

• The {array} environment from vanilla LaTeX
• The bmatrix environment from amsmath (here loaded by mathtools)

Both are shown in the below code. Choose what's best for you.

Code: Select all

\documentclass[11pt]{article}
\usepackage[T1]{fontenc}
\usepackage{mathtools}   % loads »amsmath«

\begin{document}
  \[
    \left[
    \begin{array}{cccc}
      \lambda_0 & 0 & 0 & \cdot \\
      0 & \lambda_1 & 0 & \cdot \\ \hline
      0 & 0 & \lambda_3 & \cdot \\
      \cdot & \cdot & \cdot & \cdot
    \end{array}
    \right]
  \]

  \[
    \begin{bmatrix}
      \lambda_0 & 0 & 0 & \cdot \\
      0 & \lambda_1 & 0 & \cdot \\ \hline
      0 & 0 & \lambda_3 & \cdot \\
      \cdot & \cdot & \cdot & \cdot
    \end{bmatrix}
  \]
\end{document}

Best regards and welcome to the board
Thorsten

[vaibhavtewari]

Thank You very much, it helped.

-Vaibhav

[egpuckett]

Does anyone know how to add vertical space on either side of the \hline in this example? The usual approach, namely,

foo \\[3pt] \hline \\ [3pt]
foo \\
that one can use in a table environment does not work in a matrix environment in math mode.