[MathJax] 集合 { }

hbghlyj

在TeXSE @gented的回答中:
LaTeX puts at your disposal the package braket that helps you creating beautiful sets, kets and bras for the Dirac notation. In particular

1. \set{U_\lambda}
2. \ket{\psi}
3. \bra{\phi}

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do the job as simple as that as shown below:
Let $A=\set{x\mid \psi(x)>0}$; also, given
$\ket{\psi}\in\mathcal{H}$, then $\psi(x)\coloneqq\braket{x|\psi}$.

1. Let $A=\set{x\mid \psi(x)>0}$; also, given
2. $\ket{\psi}\in\mathcal{H}$, then $\psi(x)\coloneqq\braket{x|\psi}$.

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刚发现MathJax也支持\set \ket \bra
例如
$\set{U_\lambda}$
$\ket{\psi}$
$\bra{\phi}$
\Set
$\Set{1\over2}$

hbghlyj

在这里定义了$\newcommand{\set}[2]{\left\{ #1 : #2 \right\}}\newcommand{\seq}[2]{(#1_{#2})_{#2\inℕ}}$

1. \newcommand{\set}[2]{\left\{ #1 : #2 \right\}}
2. \newcommand{\seq}[2]{(#1_{#2})_{#2\in\N}}

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可以用来写集合\(\set{U_\lambda}{\lambda \in \Lambda}\)、数列\(\seq a n\)

1. 集合\(\set{U_\lambda}{\lambda \in \Lambda}\)、数列\(\seq a n\)

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但是这样就不能再使用一元的\set (报错missing argument for \set)
相当是定义了二元的\set覆盖了原来的一元的\set