how to set vector and tensor symbols with horizontal bars above

Question

(Newbie) hi, how do I produce vector (text symbol(s)) with horizontal bar over it? Better, if possible, would be the \rightharpoonup mark above the letter (or word) that is the vector in question.(hope \rightharpoonup is the correct name for it).

I also have some tensor work to include - is there a package specifically for vector/tensor text?

At the moment I've added the bm package and that fine for bold vector symbol - but I prefer the one described above. thank you.

Answer 1

Like this?

\documentclass[a4paper]{article}
\usepackage[T1]{fontenc}
\usepackage[ascii]{inputenc}

\newcommand*{\ttensor}{\mathbin{\overline{\otimes}}}



\begin{document}
Text \( a\ttensor b \) text.
\end{document}

---

Addendum: I still owe you an answer to the question you actually asked. Christian’s answer is very good, especially because it provides the extensible harpoons you seem to be asking for (when you speak of covering a whole word); but suppose you don’t like the font that the fdsymbol package uses for that, and you want to stick to “Computer Modern harpoons” (those found in positions "28, "29, "2A, and "2B of the cmmi font); with the help of the amsmath package, it isn’t difficult to manifacture the required commands “by hand”:

\documentclass[a4paper]{article}
\usepackage[T1]{fontenc}
\usepackage[ascii]{inputenc}
\usepackage{amsmath}

\makeatletter

\newcommand*\MY@leftharpoonupfill@{%
    \arrowfill@\leftharpoonup\relbar\relbar
}
\newcommand*\MY@rightharpoonupfill@{%
    \arrowfill@\relbar\relbar\rightharpoonup
}
% These are not needed, for now:
% \newcommand*\MY@leftharpoondownfill@{%
%   \arrowfill@\lefttharpoondown\relbar\relbar
% }
% \newcommand*\MY@rightharpoondownfill@{%
%   \arrowfill@\relbar\relbar\rightharpoondown
% }
\newcommand*\overleftharpoon{%
    \mathpalette{\overarrow@\MY@leftharpoonupfill@}%
}
\newcommand*\overrightharpoon{%
    \mathpalette{\overarrow@\MY@rightharpoonupfill@}%
}

\makeatother



\begin{document}

A formula: \(
    \overrightharpoon{x}:=\overrightharpoon{\textit{counter}}
\).  Another formula: \(
    \overleftharpoon{x}:=\overleftharpoon{\textit{counter}}
\).

\end{document}

And here’s the output:

---

Second addition: On second thought, it occurred to me that perhaps the size of the covering harpoon is too big: it would look better in \scriptstyle size (when the main size is the text size). This requires a bit more effort:

% My standard header for TeX.SX answers:
\documentclass[a4paper]{article} % To avoid confusion, let us explicitly 
                                 % declare the paper format.

\usepackage[T1]{fontenc}         % Not necessary, but recommended.

\usepackage[ascii]{inputenc}     % Just to check that the source is still pure,
                                 % 7-bit-clean ASCII when you execute it, as it
                                 % was when I wrote it.
% End of standard header.  What follows pertains to the problem at hand.

\usepackage{amsmath}

\makeatletter

\newcommand*\MY@leftharpoonupfill@{%
    \arrowfill@\leftharpoonup\relbar\relbar
}
\newcommand*\MY@rightharpoonupfill@{%
    \arrowfill@\relbar\relbar\rightharpoonup
}
% These are not needed, for now:
% \newcommand*\MY@leftharpoondownfill@{%
%   \arrowfill@\lefttharpoondown\relbar\relbar
% }
% \newcommand*\MY@rightharpoondownfill@{%
%   \arrowfill@\relbar\relbar\rightharpoondown
% }
\newcommand*\overleftharpoon{%
    \mathpalette{\overarrow@\MY@leftharpoonupfill@}%
}
\newcommand*\overrightharpoon{%
    \mathpalette{\overarrow@\MY@rightharpoonupfill@}%
}

% Support for smaller size arrows:
\newcommand*\@dblsty@mathpalette[2]{%
    % Works like "\mathpalette", but macro passed in #1 must take
    % (at least) three arguments, of which the first _two_ are
    % style selections.
    \mathchoice
        {#1\displaystyle       \scriptstyle       {#2}}%
        {#1\textstyle          \scriptstyle       {#2}}%
        {#1\scriptstyle        \scriptscriptstyle {#2}}%
        {#1\scriptscriptstyle  \scriptscriptstyle {#2}}%
}
\newcommand*\@dblsty@overarrow@[4]{%
    % #1 := stretchable covering arrow
    % #2 := base style
    % #3 := style for covering arrow
    % #4 := base symbol
    \vbox{\ialign{##\crcr
        #1#3\crcr
        \noalign{\nointerlineskip}%
        $\m@th\hfil #2#4\hfil$\crcr
    }}%
}
\newcommand*\smalloverleftharpoon{%
    \@dblsty@mathpalette{\@dblsty@overarrow@\MY@leftharpoonupfill@}%
}
\newcommand*\smalloverrightharpoon{%
    \@dblsty@mathpalette{\@dblsty@overarrow@\MY@rightharpoonupfill@}%
}

\makeatother



\begin{document}

\section{Normal size}

A formula: \(
    \overrightharpoon{x}:=\overrightharpoon{\textit{counter}}
\).  Another formula: \(
    \overleftharpoon{x}:=\overleftharpoon{\textit{counter}}
\).

\section{Smaller size}

A formula: \(
    \smalloverrightharpoon{x}:=\smalloverrightharpoon{\textit{counter}}
\).  Another formula: \(
    \smalloverleftharpoon{x}:=\smalloverleftharpoon{\textit{counter}}
\).

\end{document}

In the output, you can compare the two sizes and choose your preferred one. Be aware, however, that the smaller size is inconsistent with the other uses of “over-arrows” in the amsmath package.

---

Third addition: It should be noted that (a robust version of) the two commands \overleftharpoon and \overrightharpoon is defined, in exactly the same way as shown above, by the MnSymbol package. On the other hand, as far as I know the “small” variants are genuine new ones.

Answer 2

You can use the accents package:

\documentclass{article}
\usepackage{amsmath}
\usepackage{accents}

\begin{document}

$\accentset{\rightharpoonup}{x}$

\end{document}

Answer 3

A solution with fdsymbol, using \overrightharpoon:

\documentclass{article}


\usepackage{fdsymbol}


\begin{document}

$\overrightharpoon{A}$
$\overrightharpoon{All}$

\end{document}

There's also the harpoon package and \overrightharp{A} but this does produce weird symbols, in my point of view.

Please have a look on esvect package as well, with provides nice vector arrows as accents.