Math & Science ⇒ Large double Square Brackets

[Thomas XICKIC]

Hi everyone,

I need to write down large double square brackets and I'm struggling with it. Indeed, for the usual double square brackets I use \llbracket and \rrbracket, and for the usual large square brackets I use \left[ and \right]. But I can't manage to have large double square brackets!


Thank you very much in advance !
Thomas

[localghost]

[…] Indeed, for the usual double square brackets I use \llbracket and \rrbracket, and for the usual large square brackets I use \left[ and \right]. […]

Since these commands are not from standard LaTeX, you will have to prepare a proper minimal example to show what you are doing and to avoid guesswork.


Best regards and welcome to the board
Thorsten

[Thomas XICKIC]

Well, I have the following (I simplified the inner matrices...) :

Code: Select all

\documentclass[11pt,a4paper]{article}
\usepackage{amssymb}
\usepackage{amsmath}
\usepackage{amsthm}
\usepackage{amsfonts}
\usepackage{stmaryrd}
\usepackage{dsfont}
\usepackage{xfrac}
\usepackage{mathrsfs}
\begin{document}
$$
\llbracket e^B \, V \, (e^B)^{tr} \! , &\,\; e^B \, U \, (e^B)^{tr} \rrbracket^{m n}
= \llbracket \begin{bmatrix} {V'}&{-V} \\ {V}&{0} \end{bmatrix}, \, \begin{bmatrix} {U'}&{-U} \\ {U}&{0} \end{bmatrix} \rrbracket
$$
\end{document}

It gives me small double square brackets. Since I have a matrix in between, I'd prefer large ones, that is double square brackets which have the same size than the matrices themselves (and their simple square brackets).

Is it clearer ?
Thanks

[localghost]

Never ever use $$ … $$ to introduce unnumbered displayed equations. This is TeX syntax. The corresponding LaTeX syntax to use instead is \[ … \]. Besides bad spacing those environments are not affected by the fleqn option for the document class.

Please check your examples for functionality and minimal content. At first you should fix the error that you get.

Code: Select all

! Misplaced alignment tab character &.
l.13     \llbracket e^B \, V \, (e^B)^{tr} \! , &
                                                 \,\; e^B \, U \, (e^B)^{tr}...

Just drop the ampersand (alignment character).

But that doesn't help for the actual problem. I see no problem in using the automatic scaling mechanism.

Code: Select all

\documentclass[11pt,a4paper]{article}
\usepackage[T1]{fontenc}
\usepackage{amsmath}
\usepackage{stmaryrd}

\begin{document}
  \[
    \bigl\llbracket e^B \, V \, (e^B)^{tr} \! ,\,\; e^B \, U \, (e^B)^{tr} \bigr\rrbracket^{m n}=
    \left\llbracket
    \begin{bmatrix}
      V' & -V  \\
      V & 0
    \end{bmatrix},\,
    \begin{bmatrix}
      U' & -U \\
      U & 0
    \end{bmatrix}
    \right\rrbracket
  \]
\end{document}

For the first pair some manual adjustment has been used exemplary.


Further reading:

• The amsmath manual
• The »Math mode« document

[Thomas XICKIC]

Thanks, I'm not used to \big \bigg and so on, now it works well ! (the error message is due to my quick shortening of my long document )
And thanks also for $$ to be \[ and \]... not used to it either !
Have a nice day