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I am using the physics package for braket (Dirac) notation. However, some expressions (such as the braket on the right) automatically rescale in the presence of, say, an operator (such as f hat), while others do not (such as the matrix element on the left).

I think this looks a bit ugly, especially when the equations are inline. Rather than making the matrix element bigger, however, I would like the braket to not automatically rescale, and just stay its "normal" size.

problem

The code is

$$ \mel{m}{\hat{f}}{n} = \braket{\hat{f}m}{n} $$
F Badone
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  • Welcome to TeX SX! Did you try smashing the operator? – Bernard Apr 14 '19 at 12:59
  • @Bernard thank you for your reply. I am not familiar with that macro (or any others really). How would it work in my case? Thank you very much! – F Badone Apr 14 '19 at 13:05
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    Try \smash{\braket{\hat{f}m}{n}}. Other than this, you shouldn't use the plain TeX construct $$ ... $$ for displayed equations, as it leads to bad spacing. Use \[ ... \] instead. – Bernard Apr 14 '19 at 13:12
  • @Bernard shouldn't it be \braket{\smash{\hat{f}m}{\smash{n}}? – Skillmon Apr 14 '19 at 13:22
  • @Skillmon I just tried \braket{\smash{\hat{f}m}}{n} and it works (no need to smash the second expression as well). Thank you both!! – F Badone Apr 14 '19 at 13:29
  • @Skillmon: I think the problem comes from \hat since the braket on the left is fine. – Bernard Apr 14 '19 at 13:49
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    The physics package does automatic resizing, which is normally a bad decision to do. – egreg Apr 14 '19 at 15:50

1 Answers1

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You can use \braket*. Apparently, the author didn't feel the need for specifying explicit size with \big or similar commands, like for \abs, for instance. Too bad.

\documentclass{article}

\usepackage{physics}

\begin{document}

\[
\mel{m}{\hat{f}}{n} = \braket*{\hat{f}m}{n}                           
\]

\end{document}

enter image description here

Don't use $$, see Why is \[ ... \] preferable to $$ ... $$?. I don't recommend physics either.

egreg
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