2

When I use the lmodern package (which is always), math accents tilde and bar do not change the character height (w.r.t. \left and \right). However, the hat accent makes the character taller. The file

\documentclass{article}
\usepackage{lmodern}
\begin{document}
\thispagestyle{empty}
$$
\left( \tilde A \right)
\left( \hat A \right)
\left( \bar A \right)
$$
\end{document}

renders as

enter image description here

How can I make the hat accent behave like tilde and bar?

PS. If I don't use lmodern it falls back to Computer Modern and looks like this:

enter image description here

2
  • Use manual sizing of brackets with \bigl and the like.
    – Skillmon
    Aug 31, 2017 at 8:21
  • 2
    Delimiters come in discrete sizes, so, when the material between them exceeds a certain threshold, the next size is employed. It's not that \tilde and \bar do not change the height, it's rather that the threshold is not exceeded. In most cases, \left and \right are not needed and in general fences are not required to cover the entire vertical extension of the material between them.
    – egreg
    Aug 31, 2017 at 8:41

1 Answer 1

2

Delimiters come in discrete sizes, so, when the material between them exceeds a certain threshold, the next size is employed. It's not that \tilde and \bar do not change the height, it's rather that the threshold is not exceeded.

In your examples, \big size is chosen with \tilde and \bar, but \Big size turns up with \hat.

In most cases, \left and \right are not needed and in general fences are not required to cover the entire vertical extension of the material between them. Look at the output of the following example, where also a \rhat (reduced hat) is defined (but not recommended).

\documentclass{article}
\usepackage{amsmath}
\usepackage{lmodern}

\newcommand{\shat}[1]{%
  \smash{\hat{#1}}%
  \vphantom{\bar{#1}}%
}

\begin{document}

No change:
\[
\left( \tilde{A} \right)
\left( \hat{A} \right)
\left( \bar{A} \right)
\]

Change:
\[
\left( \tilde{A} \right)
\left( \shat{A} \right)
\left( \bar{A} \right)
\]

Better:
\[
(\tilde{A})
(\hat{A})
(\bar{A})
\]

\end{document}

In my opinion, the last example is the one to be followed.

Note: $$ should never be used in LaTeX, see Why is \[ ... \] preferable to $$ ... $$?

enter image description here

1
  • Thank you! The paired delimiters come from a third macro, so I can not change that. I ended up redefining \hat has \shat. Maybe later... I will smash all accents. :)
    – Mankka
    Aug 31, 2017 at 10:17

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