Why are bra and ket defined in the official package braket.sty
in two different ways (\bra
, \Bra
and \ket
, \Ket
)?
I do not understand why there exists the command \bra
with non-scalable delimiters. For stylistic reasons, I intuitively used the capital letter versions. Were you ever confronted with the second non-scalable version?
See the short example for bra:
\documentclass{article}
\usepackage{amsmath}
\usepackage{braket}
\begin{document}
\begin{align*}
\Bra{\frac{1}{\sqrt{2}}\left(\uparrow + \downarrow\right)}
&=\frac{1}{\sqrt{2}}\left(\Bra{\uparrow}+\Bra{\downarrow}\right)\\
\bra{\frac{1}{\sqrt{2}}\left(\uparrow + \downarrow\right)}
&=\frac{1}{\sqrt{2}}\left(\bra{\uparrow}+\bra{\downarrow}\right)\\
&=2 222 22\\
&=2\mathinner{222}22
\end{align*}
\end{document}
Understanding of the package's definition
For amsmath noobs like myself, the last two lines in the align environment review what \mathinner
does (if you look at the braket.sty
's package source code). The package defined the commands the following way:
\def\bra#1{\mathinner{\langle{#1}|}}
\def\ket#1{\mathinner{|{#1}\rangle}}
\def\Bra#1{\left\langle#1\right|}
\def\Ket#1{\left|#1\right\rangle}
mathtools
' command\DeclarePairedDelimiter
for the delimiters? You cannot apply user-defined scaling like\Bigg
either (you wrote about it in your answer below). – strpeter Dec 9 '13 at 16:02