Math & Science ⇒ Norm symbol to correspond argument height

[Thegal]

I want to have a norm in my equation such as ||x||. However, my argument x is composed of fractions and thus the vertical lines should be longer.

Using the commands \lVert and \rVert, I get small vertical lines. How would I be able to have them resized?

[Stefan Kottwitz]

Hi Thegal,

welcome to the board!

Use \left and \right for variable size delimiters:

Code: Select all

\[
  \left\lVert \frac{x}{y}\right\rVert
\]

delimiters.png (1.58 KiB) Viewed 29090 times

Stefan

[localghost]

It is suggestive to define a corresponding command. The mathtools package offers a helpful structure.

Code: Select all

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

\DeclarePairedDelimiter{\abs}{\lvert}{\rvert}
\DeclarePairedDelimiter{\norm}{\lVert}{\rVert}

\begin{document}
  $\norm{x}$
  \[
    \norm*{\frac{x}{y}}
  \]
\end{document}

The package manual has more details about this and other of its interesting features.


Best regards and welcome to the board
Thorsten