欢迎来到QSD妙妙屋！

公告板

关于本网站的目的，请参见这篇文章： Day one of this site。

➡️➡️➡️ QSD减肥进行时💨💨！！

A Bizzard Self-Intro…?

• 🤖QSDQSB
• 🔬24’ Maths&Stats at Ox
• 🦃From The Queen’s College, whose logo consists of three turkeys
• ☕️Americano addict
  • ⬆️Might trigger something if you click the coffee emoji
• 📷Photography rookie
• 🎸Amateur music composer
  • 🎹This guy really used to know piano, but not anymore
  • 🎻So-called 网易音乐人
• 📱Wechat $\times\times\times\times\times\times$; Would argue reasonably straightforward to guess based on this site.
• 🎮Civilization VI! But suck at it :(
• 🧱Lego 76042+71043+21327
• ⚠️The previous red brick has nothing to do with Keble College.
• 🧙‍♂️𝕽𝖆𝖛𝖊𝖓𝖈𝖑𝖆𝖜🦅
• 🕶S.H.I.E.L.D. agent
• 📺YPM! Silicon Valley! Better Call Saul! Disenchantment!
• 👾Emoji crusher(as you can see from this page)
• 🎨马卡龙色系yyds
• 🐱骨灰级猫猫粉
• 🐟enjoy 摸鱼 every day
• 🏃努力减肥中(但愿)
• 🇨🇳Geographically Hangzhounese, spiritually Shanghainese

‼️Note that every picture in this website is shot by QSD himself, or his beloved friends.

What’s New!

“有哪些文件夹刚刚被新建了呢？”

What else should we do before publishing this page?

• test latex: \(\small\forall x \in \mathbb{R}, \exists \,\varepsilon >0 \,\,s.t.\)

That was too easy, let’s try:

Argument Principle

Suppose that $U$ is an open set and $f: U \rightarrow$ $\mathbb{C}$ is a meromorphic function on $U$. If $B(a, r) \subseteq U$ and $N$ is the number of zeros (counted with multiplicity) and $P$ is the number of poles (again counted with multiplicity) of $f$ inside $B(a, r)$ and $f$ has neither on $\partial B(a, r)$ then \(N-P=\frac{1}{2 \pi i} \int_{\gamma} \frac{f^{\prime}(z)}{f(z)} d z,\) where $\gamma(t)=a+r e^{2 \pi i t}$ is a path with image $\partial B(a, r)$. Moreover this is the winding number of the path $\Gamma=f \circ \gamma$ about the origin.

Don’t know what this is? It’s quite simple, just get a maths degree and you will see.