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- What does sgn mean? - Mathematics Stack Exchange
NB the definitions of $\mathop {\rm sgn} (0)$ vary between $0$ and $1$ If $0$ is a plausible argument, you should assure yourself of the definition of $\mathop {\rm sgn}$ at $0$ in your context
- 为什么要定义符号函数 sgn x？ - 知乎
\text {sgn } (x) ⋅ \frac {1} {2}x^2 值得注意的是，符号函数的自变量并不直接等于积分变量，而是取被积表达式中 绝对值内的式子。
- sgn函数 - 知乎
sgn函数 阶跃函数，数学上的符号函数或者计算机语言中的返回函数。 Sgn 函数 返回一个 Variant (Integer)，指出参数的正负号。 语法 Sgn (number) 必要的 number 参数是任何有效的数值表达式。
- 请问符号函数自己卷自己，即sgn t * sgn t等于多少？ - 知乎
请问符号函数自己卷自己，即sgn t * sgn t等于多少？ 自己比较垃，发现在算 sgn t * sgn t 的时候出问题了：无论 sgn t = 2u (t)-1 还是 sgn t = u (t)-u (-t)，我… 显示全部 关注者 21 被浏览
- How does one compute the sign of a permutation?
The sign of a permutation $\sigma\in \mathfrak {S}_n$, written $ {\rm sgn} (\sigma)$, is defined to be +1 if the permutation is even and -1 if it is odd, and is given by the formula
- sgnx函数在高等数学上都有什么用法？ - 知乎
这是一道 USAMO 压轴，当然标答不是积分不等式，但利用积分不等式的结论和 sgn函数，进行巧妙构造就可以做出。 (这题是挺难的) 给个提示吧，先证明如下不等式：
- Prove that sgn is a homomorphism from $S_n\to\ {1,-1\}$.
This is a matter to which one must dedicate some attention, because the fact that, for all $\sigma$, "$\sigma$ can be decomposed into an odd number of transpositions" and "$\sigma$ can be decomposed into an even number of transpositions" are mutually exclusive is basically tantamount to proving that $\operatorname {sgn}$ is a well-defined
- Fourier Transform of $sgn (t)$ - Mathematics Stack Exchange
I found multiple sources online stating the FT of sgn$ (t)$ is just $\frac {1} {i \pi \omega}$ My previous comment is wrong though, as I was using the formula for taking FT of integrals wrong
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