MathJax 的基本运用

Reference:
https://math.meta.stackexchange.com/questions/5020/mathjax-basic-tutorial-and-quick-reference

1、 绝对值和范数（Absolute values and norms）

The absolute value of some expression can be denoted as \lvert x\rvert or, more generally, as \left\lvert … \right\rvert. It renders as |x| | x | .

The norm of a vector (or similar) can be denoted as \lVert v\rVert or, more generally, as \left\lVert … \right\rVert. It renders as ∥v∥ ‖ v ‖ . (You may also write \left|…\right| instead.)

In both cases, the rendering is better than what you’d get from |x| or ||v|| , which render with bars that don’t descend low enough and sub-optimal spacing. |x| | x | or ||v|| | | v | | .

It was typeset as

|x|,||v||⟶|x|,∥v∥ | x | , | | v | | ⟶ | x | , ‖ v ‖

2、Arbitrary Operator

If an operator is not available as a built-in command, use \operatorname{…}. So for things like

arsinh(x) a r s i n h ( x )

write \operatorname{arsinh}(x) since \arsinh(x) will give an error and arsinh(x) has wrong font and spacing: arsinh(x).
For operators which need limits above and below the operator, use \operatorname*{…}, as in

Resz=1(1z2−z)=1 Res z = 1 ⁡ ( 1 z 2 − z ) = 1

为什么 z=1 z = 1 不是在 Res R e s 的下面

max∥x∥=1∥Ax∥ max ‖ x ‖ = 1 ⁡ ‖ A x ‖

max∥x∥=1∥Ax∥ max ‖ x ‖ = 1 ‖ A x ‖

∥x0∥ ‖ x 0 ‖
ex=limn→∞(1+xn)n e x = lim n → ∞ ( 1 + x n ) n

limx→1x2−1x−1 lim x → 1 x 2 − 1 x − 1