# What is the best symbol for vector/matrix transpose?

What is the best or most popular symbol for vector/matrix transpose? I have used simply ^T, for example $c^T x$. I think it is ugly, mainly because it is a little too big compared with vector variables usually denoted by lower-case characters. Can you suggest a better one?

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Why does it look ugly? Too big? Too high? Too what? – Werner Oct 5 '11 at 22:16
That's exactly what I use! :) – egreg Oct 5 '11 at 22:18
I use M^\top. (For orthocomplements of vector spaces, I similarly use V^\bot.) Using T or t as a superscript is problematic in disciplines where they are modestly likely to occur as an actual variable, especially one which might occur in an exponent. I choose \top and \bot because they are more obviously abstract symbols, and not variables. – Niel de Beaudrap Oct 5 '11 at 22:21
(Incidentally, while I am opinionated on this subject, the very fact that it is strongly subject to opinion makes it a somewhat questionable topic for a StackExchange site...) – Niel de Beaudrap Oct 5 '11 at 22:25
Also, questions about mathematical notation are at best borderline on-topic. Maybe, @Chang, you can be more specific what you want to see. “I'm too lazy” is not a good way to ask questions here. – Caramdir Oct 5 '11 at 22:27

\documentclass{article}
\usepackage{amssymb,amsmath}
\usepackage{relsize}
\begin[document}
$A^T\ A^{\mathsmaller T}$
\end{document}

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A^{\tau} looks best for me. I tried others but T was still too big.

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It's always difficult to answer questions for "the best" or "most popular". As is mentioned, these are typically opinions. But you did say that your objection was the fact that the "T" symbol was too big. Therefore, I would recommend the \intercal symbol to produce a "T" which isn't so big. Also, writing the vectors and matrices in bold seems, in my opinion, to make it look a little better. Try the following code:

\documentclass{article}
\usepackage{amsmath,amsfonts,amssymb}
\begin{document}
$\textbf{A}^\intercal$\\
$\textbf{c}^\intercal \textbf{x}$\\
$c^T x$\\
$\textbf{M}^\top$
\end{document}


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It is better to use \mathbf rather than \textbf – Aditya Jul 16 '12 at 21:11

There are some good suggestions regarding which symbol to use, it is a good idea to define your own macros for indicating matrices, vectors, and transpose, so that you can write:

\MAT A \VEC b^\TRANSPOSE


This will make it easy to change the notation in the future, if you ever need to do so. In addition, the source is more readable than \mathbf A \mathbf b^\intercal etc.

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Conjugate transpose is in physics often denoted by ^\dagger because of its association with adjoint operators.

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Personally I often use the conjugate transpose instead. For real matrices this concept coincides with the transpose, for matrices over the complex field the conjugate is usually what you want anyway. The conjugate transpose of a matrix A is denote A^*.

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The Comprehensive LaTeX Symbol List says the following:

Some people use a superscripted \intercal for matrix transpose: A^\intercal. (See the May 2009 comp.text.tex thread, "raising math symbols", for suggestions about altering the height of the superscript.) \top, T, and \mathsf{T} are other popular choices.

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 Thanks a lot! The book I am currently citing a formula from uses exactly what latex produces with \mathbf{w}^\top for a transposed vector. So I am going to go with this variant... (\intercal would be the second choice, but T and mathsf{T} look ugly in my opinion) – Philip Daubmeier Jun 6 '12 at 15:12