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I need the symbol <<< (left rotation). Now from TexStudio help, I found it as \lll. But when I use it, I get an error Undefined control sequence ... \lll. How to fix it?

  • 5
    \usepackage{amssymb} – Steven B. Segletes Jan 31 '14 at 18:02
  • 1
    You need something that supplies that symbol, like amssymb. There are others as well. See the Comprehensive LaTeX Symbol List. – Werner Jan 31 '14 at 18:03
  • LaTeX has a very large supply of packages for doing several things. It's simply impossible to load all of them, so they're loaded on user's demand. In the list linked by Werner you easily find what \usepackage{...} command is needed for making a certain symbol available. – egreg Jan 31 '14 at 18:10
4

Just for fun, a poor man's solution for \lll and \ggg:

\documentclass{article}
\usepackage{amssymb}

\makeatletter
\newcommand*{\pmlll}{%
  \mathrel{%
    \mathpalette\@lllggg<%
  }%
}
\newcommand*{\pmggg}{%
  \mathrel{%
    \mathpalette\@lllggg>%
  }%
}
\newcommand*{\@lllggg}[2]{%
  % #1: math style
  % #2: symbol
  \sbox0{$\m@th#1#2$}%
  \copy0 %
  \kern-.6\wd0 %
  \copy0 %
  \kern-.6\wd0 %
  \copy0 %
}
\makeatother

\begin{document}
\[ a \lll b \ggg c ^{d \lll e \ggg f} \]
\[ a \pmlll b \pmggg c ^{d \pmlll e \pmggg f} \]
\end{document}

Result

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