Emacs - Notmuch
Introduction Notmuch is a mail system1. It can efficiently manage a fairly large number of emails. Particularly, it supports fast email searching and filtering based on tags, which is extremely …
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C++ - Singleton
Singleton plays an important role in program architecturing for its global visibility. For instance, system parameters are usually structured as a singleton. What deserves to be noticed, a singleton …
Gaussian Distribution
Probability density function $X \sim \mathcal{N}(\mu, \sigma^2)$ \begin{align*} p(x) = \frac{1}{\sqrt{2\pi}\sigma} \exp\left[-\frac{(x-\mu)^2}{2\sigma^2}\right] \end{align*} Distribution function …
Z Transform
Given a time domain discrete signal, i.e., a sequence, it can be represented in the complex frequency domain by Z transform. It is essentially an extension of discrete time Fourier transform (DTFT). …
Laplace Transform
Given a time domain continuous signal, it can be represented in the complex frequency domain by Laplace transform. It is essentially an extension of Continuous Fourier transform. Definition Bilateral …
归去来兮辞
序 余家贫，耕植不足以自给。幼稚盈室，瓶无储粟，生生所资，未见其术。亲故多劝余为长吏，脱然有怀，求之靡途。会有四方之事，诸侯以惠爱为德，家叔以余贫苦，遂见用于小邑。于时风波未静，心惮远役，彭泽去家百里，公田之利，足以为酒。故便求之。及少日，眷然有归欤之情。何则？质性自然，非矫厉所得。饥冻虽切，违己交病。尝从人事，皆口腹自役。于是怅然慷慨，深愧平生之志。犹望一稔，当敛裳宵逝。寻程氏妹丧于武昌，情在 …
ZC
Introduction The Zadoff-Chu (ZC) sequence1 is named after Solomon A. Zadoff and D. C. Chu, which is a constant amplitude zero auto-correlation (CAZAC) sequence2 with its cylically shifted versions …
Wiener Filter
设观测信号\(x(t)\)为期望信号\(s(t)\)和噪声信号\(n(t)\)的叠加，也即 \begin{align*} x(t) = s(t) + n(t). \end{align*} 其中，\(s(t)\)和\(n(t)\)是宽平稳过程，且相互联合宽平稳，观测信号\(x(t)\)和期望信号\(s(t)\)的自相关函数和互相关函数分别为\(R_x(\tau)\)、\(R_s(\tau)\)和 …
Virtual Console Switch
Unix and Linux operation systems (OS) originally provided textual interfaces only, but now, we can already enjoy the perfect graphic experience through their desktop systems, e.g. Gnome, KDE, XFCE. …
SSH
Secure shell (SSH) is the most popular and efficient method for remote access. This post introduces SSH relevant issues, from installation to configuration. Installation Take Archlinux for instance …