LaTeX forum ⇒ Math & Science ⇒ Extended Vector Arrow

[ghostanime2001]

How do you put an arrow above a vector as in vector AB or vector ABC? I have used \vec but this command works for only single letter vectors but what about multiple character vectors?

[tommytex]

hi (:

Use this.

\documentclass[12pt]{article}

\begin{document}
$$\overrightarrow{ABC}$$
$$\overrightarrow{ABCDEFG}$$
\end{document}

or the package esvect

greez tommy

[localghost]

[…] Use this.

\documentclass[12pt]{article}

\begin{document}
$$\overrightarrow{ABC}$$
$$\overrightarrow{ABCDEFG}$$
\end{document}

[…]

Never ever use $$ … $$ for unnumbered equations (look here for the reason).


Thorsten

[tommytex]

sorrry thorsten

i hoope i can give a better answer next time

tommy

[ghostanime2001]

the problem with \overrightarrow is that the arrow touches the top borders of the letters. Are there packages to customize vector arrows ?

[cgnieder]

the problem with \overrightarrow is that the arrow touches the top borders of the letters.

This depends on the font you're using:

\documentclass[margin=.75cm]{standalone}
\usepackage[T1]{fontenc}
\usepackage{amsmath}
\begin{document}
$\overrightarrow{AB}$
\end{document}

ora1.png (2.06 KiB) Viewed 79273 times

\documentclass[margin=.75cm]{standalone}
\usepackage[T1]{fontenc}
\usepackage{libertine}
\usepackage{amsmath}
\usepackage[libertine]{newtxmath}
\begin{document}
$\overrightarrow{AB}$
\end{document}

ora2.png (1.82 KiB) Viewed 79273 times

\documentclass[margin=.75cm]{standalone}
\usepackage[T1]{fontenc}
\usepackage{amsmath}
\usepackage{MnSymbol}
\begin{document}
$\overrightarrow{AB}$
\end{document}

ora3.png (1.84 KiB) Viewed 79273 times

Regards

[ghostanime2001]

can the arrow be moved just a little bit upward ?

[tommytex]

actually i looked it up and found some nice usage of "esvect" where it works indeed.... using a command called \vv

unfortunately, the page is in german but i think you can get its meaning anyway

see http://www.latex-pfeile.de/ you will have to scroll down a bit

[ghostanime2001]

that's what I wanted to use but if only it can be moved up a little, what is the full command for \vv ? like I know it has to be made up from other commands, so maybe there's a parameter for height and if that could be changed the height of the arrow could also be changed.

[cgnieder]

what is the full command for \vv ?

That actually doesn't tell you much, except that it has a starred variant:

\def\vv{\@ifstar{\vvstar}{\vecteur}}

\vvstar calls itself \vecteur which in turn calls ... The code of esvect.sty is only 32 lines long, you could look it up yourself.

maybe there's a parameter for height and if that could be changed the height of the arrow could also be changed.

The macro that actually places the arrow over the letters is the following:

\def\overvect@#1#2#3{\vbox{\ialign{##\crcr%
 \noalign{\kern-.7pt\nointerlineskip}#1#2\crcr%
 \noalign{\kern-.3pt\nointerlineskip}$\m@th\hfil#2#3\hfil$\crcr}}}

It actually moves the arrow closer to the letters by -.3pt. Changing this value shifts the arrow vertically, so you can play until you find something you like:

\documentclass[margin=5pt]{standalone}
\usepackage{esvect}
\begin{document}

% original:
$\vv{AB}$

% changed definition:
\makeatletter
\def\overvect@#1#2#3{\vbox{\ialign{##\crcr%
 \noalign{\kern-.7pt\nointerlineskip}#1#2\crcr%
 \noalign{\kern3pt\nointerlineskip}$\m@th\hfil#2#3\hfil$\crcr}}}
\makeatother

$\vv{AB}$

\end{document}

vect.png (3.71 KiB) Viewed 79262 times

Regards