问题描述
我正在尝试使用 ket 符号，该符号通常以 \ket {\ psi} 编写。但是，在 $$ ... $$ 中编写时，这不起作用。使用 IPython.display 编写时，这也不起作用。
I am trying to have the ket symbol which is usually written in latex as \ket{\psi}. However, this doesn't work when written within the $$ ... $$. This also doesn't work when written using IPython.display.
推荐答案
$ latex
** \documentclass{article}\usepackage{amsmath}\begin{document}
... chatter chatter ...
* \show\ket
> \ket=undefined.
所以你的 \ket 宏即将到来从一些包或其他我不知道它是什么。这并不能解释为什么它在 $$ ... $$ 中不起作用 - 你必须努力使它在显示数学中不起作用 - - 但它确实解释了为什么它在IPython中不起作用：在IPython的罐装TeX环境中没有加载哪个包（或者）IPython对TeX数学输入语言的仿真不包括这个宏。
So your \ket macro is coming from some package or other which I don't know what it is. This doesn't explain why it doesn't work in $$ ... $$ -- you have to work at it to get things to not work in display math -- but it does explain why it doesn't work in IPython: whichever package this is isn't being loaded in IPython's canned TeX environment (or) IPython's emulation of TeX math input language does not include this macro.
这是一个合理的原始数学符号定义，它应该在显示模式下正常工作。我不知道你是否可以逐字地将它放入IPython中，但你至少应该能够在需要时写出扩展名（例如 $$ \ leftft | \ psi \ right \\ \\ _ $$ $ ）
Here's a reasonable definition in terms of primitive math symbols, which should work fine in display mode. I don't know if you can put this into IPython verbatim, but you should at least be able to write out the expansion longhand when needed (e.g. $$ \left| \psi \right\rangle $$)
\newcommand{\ket}[1]{\left|{#1}\right\rangle}
\newcommand{\bra}[1]{\left\langle{#1}\right|}
编辑：使用LaTeX首选接口定义宏，而不是原始 \ def 。
define macros using LaTeX preferred interface, rather than primitive \def.
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