景田日志

BU篮球半年记

sports

来BU打球半年有余，从一开始的不太适应到现在持续地和各种水平的选手过招，见识了不少人，也见证了自己的成长。常来的球友不少，偶尔光顾的众多，不断地观看和切磋，为了自己热爱的运动挥洒汗水。

Basketball Court in Shenzhen

sports

在深圳找个合适的篮球场真是不容易。到了夏天太阳暴晒，无阴凉处五点以前基本上不用考虑。

Comparison of Time-Frequency Transforms

math

Stefan Scholl made a nice comparison between different kinds of time-frequency transforms available: Fourier, Gabor, Morlet or Wigner. The paper on Arxiv is linked here. In…

Profiling

With Intel OneAPI

programming

The Intel profiler VTune and Trace Analyzer are now bundled in the OneAPI toolkit. It works best for C/C++ codes, and decent for Fortran. I have some good time using the GUI…

Haskell

programming

那天无意中发现Qusai练手写了一点的Haskell，想着这小子也挺与时俱进的嘛，终于不再整天抱着那Python了。但想想看我对于Haskell的了解也就停留在知道这是一门纯粹的函数式编程语言，觉得不行，还是得多了解一点，于是翻开了Haskell的维基，从最基础的开始学起。看完初级篇，觉得该教程写得非常出色。对于没有编程基础但是懂数学的人，我相信…

R Notes

programming

R is popular among statisticians and biologists. It is one of the most commonly used languages in data analysis.

Nushell

A new type of shell

software

I am glad to see the evolving of modern shells. I enjoy using zsh, but now there are even fancier ones: nushell. It highlights three features:

Experiment Design

How to perform trustworthy experiments

science

Any successful experiment requires careful design beforehand. There are systematic methods for ensuring the validity of test results.

Matplotlib

software

Matplotlib is a great library, but there are still issues. Over 20 years of development and 3 major version releases, Matplotlib has evolved into a giant library.

Practical Tricks in Signal Processing

math

Select the best smoothing methods that works for your data. Start from simple methods first.

Rust

programming

Rust是我一直想了解的语言；唯一的障碍可能就是即使会了一些Rust，短期内看不到哪里能够实际用上。然而学习一门新东西，并不总能立刻看到用途的。

The Effectiveness of Modern CPUs

hardware

programming

While watching this Cppcon 2021 video

瑞典游记

travel

瑞典，北境上的富庶王国。第一次踏上欧洲的领土，竟然是飞越了大西洋，途径冰岛，来到了波罗的海之旁。…

Gravity Wave

math

Make analogies of what you don’t know to what you know.

JavaScript

programming

圣诞假期到现在陆陆续续在学习一些JavaScript，期望触类旁通，理解语言的共性和不同。JavaScript作为常年霸榜的编程语言，它的兴起和流行和互联网的发展密不可分。在HTML5的时代，Javascript的地位也依旧没有任何被撼动的趋势，只是出现了更多后继衍生品，比如TypeScript。然而，现代JavaScript的这套骨架被历任程序…

Blunt Body Problem in Hydrodynamics

math

At first sight, this seems to be an easy problem: there should be some kind of analytical solution given an ideal shape of the obstacle, say a cylinder in 2D or sphere in…

Parallel Programming Concepts

programming

很长时间我都没能准确理解多进程之间的工作关系，特来梳理一下。名词上可能不太准确，但是尽量争取概念上是对的。

Kinetic Plasma Simulations

math

昱曦向我推荐了一个Anatoly Spitkovsky的动力学模拟的讲座，

Development Report For Vlasiator.jl

programming

最近给了一个线上的有关Vlasiator.jl的报告,

Fourier Analysis

math

I hate it when people make simple things complicated, and complicated things impossible.

Cross-Wavelet Transform

math

Before we talk about cross-wavelet transform (CWT)¹, we need to understand wavelet transform (WT). Before we learn wavelet transform, we’d better have a good understanding…

Linux Memory

hardware

software

Since I started working with Vlasiator, I have encountered many issues related to memory usage. Now it’s a good time to go over some basics in Linux’s memory management.

Ubuntu Soundtrack

hardware

software

I’ve been using Ubuntu 18 for quite some time now. One thing that is frequently not working properly is the sound output switches. It happens from time to time that if I…

Advanced Python

programming

Good languages stop you from writing stupid codes; bad languages allow you to write more stupid codes. Do not live on ancient code until death! Latest things are not…

简报制作

visual

作报告的时候，我们可以尝试加入电影一样的运镜方法。这方面比较亮眼的产品是一款叫Prezi的在线编辑器。用它做出来的展示品不仅可以实现运镜效果，还可以在视频及视频会议中达成类似动态展示的效果。官方支持里面竟然没有中文，这是有点令人意想不到的。

Refactoring

programming

所谓refactoring，指的是在不改变程序外部功能的情况下对内部结构进行优化调整，

Evolution of Programming

programming

In the 20th century as a programmer, you have to learn and write machine code. In the 21st century, it is no longer the case.

N-Body Simulation

math

programming

N体问题是力学中的著名基础问题，当\( N \)时的解析解迄今依旧是个问题，仅在某些特殊情况下（比如其中若干个粒子/物体的质量相对极小）有解析解。 N体问题也是粒子模拟中的经典问题，分子动力学的入门例子就是一个势场中粒子的相互作用问题。

Green’s Function

math

最早在数理方程的时候接触到格林函数，但一直是懵懵懂懂的。在实际的演算中几乎用不到，于是一直也没真明白。稍微回顾一下。

Geometric Algebra

math

“A unified mathematical language for the whole of physics.” - David Hestenes

Kalman Filter

math

The first time I’ve heard about Kalman filter is during my exploration of image feature extraction. A MATLAB demo shows how Kalman filter can be used to track passengers in…

Debugger

programming

One way of debugging segmentation fault is using GDB. It is such a deep learning curve that no one ever claims he or she fully understands the complete usages. Here is just…

Data Transfer

software

scp: fast, straightforward, speed shown by default.

IO Hardwares

hardware

Data access speed is important. In many applications, it is more important to have faster data access speed than higher CPU frequency.

语言小论

language

晚上Maxime谈论起法语中的阴性词和阳性词，我问他这有什么规律可寻吗。他说完全没有，就是说多了一个一个记下来就好；如果你用错了也没关系，反正大家都听得懂。而如果是个外国人讲错了就更无所谓了，他说完全不会由于这个去评价这个人如何。这倒是让我思考起语言中语法规范的严谨性和通俗性。其实现在各个国家的语言，细究起来都难言“规范”，总是存在着各式各样的习…

Make for a Better World

Towards a robust compilation process

programming

software

There are many different types of make system, among which the most famous one is GNU make. make is a tool designed for compiling programs into executables, but it also can…

Compilers

programming

Check the post How to Install GCC Compiler on Ubuntu.

Chromium Browsers

software

When I bought a new laptop a few months ago, I decided to get a new Win10. Now the default browser on Win10 is Edge, which is built upon Google’s Chromium kernel. Things…

Remote Access through SSH

software

Tutorial on proxy jump

Linux Distros and WSL2

software

Being annoyed by the CENTOS linux distro from Redhat, I’ve decided to take a look at some latest distros available. There are several amazing ones already! If I have time, I…

Command Line Tools

Useful tips and tricks

software

When using properly, command line is often the easiest and fastest way to get tasks done, even though the same thing can be also accomplished in other ways like using…

Software Installation

Where we can do better

software

The first thing to tell if one is familiar with codes is whether he or she can compile it. As I move to new group using a completely different code, this is a good chance to…

启程赫尔辛基

travel

欧洲人习惯的月日记法和中国一致，但是和美国是反的，估计单这就能闹出不少乱子。咱既然来了欧洲，当然也要入乡随俗了。

Cappella

music

ARM-64 Architecture

Performance Benchmark

hardware

programming

There is probably a ongoing trend of adopting arm chips to commercial and even high performance computing world. I got a chance to try out the new Raspberry Pi 4 with 64-bit…

我与数据可视化的那点事儿

visual

学习工作中反复和图像打交道，更能感受到人类的视觉动物本性。五感中，视觉可谓是信息量最大的输入，也同时深入影响着抽象的思维逻辑。我们力图在复杂中寻找简单，高度提炼的数据是关键的一环。

Practicing C++

programming

If scientists read coding standards and recommendations like C++ Core Guidelines in the first place, then it is less likely that science codes will be poor in performance…

Mac Setup

Software installation and usage on Mac OS

software

Part of this post originates from Dan Welling’s article Your Mac as a Linux Box.

Passing Arguments

programming

The design of high level program structures is very challenging. One common headache for me is how to pass arguments between function efficiently.

Editors

Emacs, Vim, Atom, VSCode, and Typora

software

I have just learned from the Juno team that they are going to shift towards Visual Studio Code in the future. The main decision behind this is that after GitHub was bought…

Git Version Control

visual

I haven’t considered myself a programmer until very recent years. As a proof of that, 2017/08/28 is the first day I use Git. My experience of using a version control system…

Learning AMReX

programming

AMReX examples are organized in separate folders. This looks nice to me, similar to the building blocks of OpenFOAM.

Lyrics Collection

music

在你身边路虽远未疲倦伴你漫行一段接一段

Colormaps

visual

A colormap is matrix of values between 0 and 1 that define the colors for graphics objects such as surface, image, and patch objects. Colormap is extremely important in…

Figure Processing

visual

I have tried an excellent PNG file compressor online: TinyPNG. Usually this can compress a figure by about 60% without lossing visually detectable quality! This should…

Wavelet Transform

math

There are already many nice introduction of wavelet transform, like here and the following video. This is my simple note on WT while reading those tutorials.

Computer Hardware for Coding

Reprint From BioJulia

programming

hardware

Here is a post for scientists on how to write nice codes given the knowledge of computer hardwares. Very nice.

Internet Connection

software

hardware

Since I moved to the new apartment, the intermittent internet interruption has been bothering me. However, this provides me a good opportunity to learn about basic network…

Object Oriented Programming

Personal experiences

programming

Since the 1990s, the idea of object oriented programming is prevailing in the science community. Scientists had started to code in Fortran in the 1960s, and later in C, and…

Shared Library

What is it and how to use it

programming

This is a collection of knowledge about shared/dynamic libraries.

Magic Angle

The magic behind MRI and reinforced rubber hose

science

What is magic angle, and how does it work??

MPM与CG特效

programming

visual

任天堂大乱斗

game

任天堂大乱斗是一款神奇的游戏。2018年底上市的Switch游戏，多达三位数的基础人物、地图场景和总时长28小时的游戏音乐；大小地图分列的单人模式；不同于以往的格斗模式创新——一款有野心，也有完成度的任天堂作品。

Behaviour of BibLaTeX

Details you may neglect

latex

biblatex will display author’s first name to distinguish different authors with the same last name. You may accidentally have the same author but different spelling, however…

三番杂记

travel

在湾区坐了一天车，开了一天车，地方没多大，堵车可一点也不少。我之前错误地估计了三番的地理区划，多待的一天选择住在了市中心，结果三番市里离圣何塞竟有一个小时车程，折腾来去大费周章在了路上。湾区车多，路线选择却仅有两条，上下班的高峰期天天堵车，红色的尾灯连成一片，无可奈何中或许焦虑感顿增——然而也有些许的温情。回三番的路上，夜幕降临，租的车不熟，忘了…

Using latexdiff

Compare and show the differences between files

software

latex

Compare the differences between files is a tedious task. However, if you pick the right tool, it may become as easy as one line command.

Paraview Usage Notes

visual

Paraview is a powerful tool for visualization and postprocessing, but it requires some effort to get familiar with it. The learning curve suddenly becomes steep at some point.

Ole Solskjaer Returning to MU

sports

今天我看着曼联的新闻，两眼嗔满了泪水。我认识了你已经十几年，我看到你教练的新闻已经近五年。我知道你会回来的；一定会的。但这样回来，没有比这样回来更好的情景了。

Remote Access through X11

XWindow forwarding

visual

When you ssh to a remote server, you may need to open graphic software through x11. Check the following things to avoid the displaying error X11 forwarding request failed on…

Making Videos from Figures

visual

An animation is simply frames of figures. It is pretty helpful to be proficient at generating a set of figures and combining them into a video. However, naively combining…

Biostation Retreat

travel

系里组织的第一次博士生的出游活动，一看是临近北密的学校的生物站，时间允许二话不说就去了。五年级的博士生只有我跟毅轩两人，其他都是些年轻的面孔。同届的学生估计大都很忙吧。作为系里五年来第一次的集体出游，真是要给研究生会的同学点个赞。

新加坡之行

travel

这次出行似乎有点仓促，什么功课都没做就直接收拾行李上了飞机。可能对于语言没有障碍且大不到哪里去的地区没有什么心理负担吧。但我也真的心大，仿佛回到了几十年前人们出行的方式。飞机预计早上六点多降落，七点钟从机场出来，会场也不知道叫啥，酒店也不知道叫啥。会议的议程手册压根儿没看，指甲刀和临时寄物柜的英文也不知道怎么说。这2G网看来要带我走天下了。

仙台之行

又是一年MOP

travel

借着到日本开会的机会，我第一次真正走进了这个神奇的国度。在讯息发达和文化融合的今天，称得上陌生的东西不多，但可以思考和观赏的地方也不少。

麦迪逊游记

比赛，亦或旅游

travel

Madison离Ann…

Introduction to CNN

math

You can watch the video for a nice walk-through. Here is just some notes from that video. A nice interactive playground based on tensorflow can be found here.

Plotting of Streamlines

visual

The built-in streamline function of Matplotlib/MATLAB is not proper for scientifically visualizing field information.…

DC 三番记

travel

第三次来华盛顿了，一开始找路的时候才发现，还是不够了解这座城市。下了地铁找个路南北都能弄反，回忆了半天愣是没想起来曾经住过的宾馆在哪里。直到重新绕着市中心转了一圈，在中国城里曾经吃过的馆子再来一遍，才让过往的记忆浮出水面，重焕光彩。最终才发现，现在住的Marriot，离曾经的Renaissance，不过一百米的距离。我见识过的财政部、国防部、白宫…

洛杉矶杂记

travel

第一次来洛杉矶，来到了加州大学洛杉矶分校。这时仍是他们的夏季学期，但学校里却依然人潮涌动。来回两遍，我已经对这里的方位烂熟于心。…

东游记

从安娜堡到纽约

travel

白雾飞溅成雾，阳光幻化成虹；隆隆落水相伴，偏偏海鸥共舞。

科罗拉多杂记

又是一年MOP

travel

用一周，了解一座城。

墨西哥杂记

圣诞新年七日谈

travel

我把旅行中零散的记录收集在一起，再额外补充一些，作为17年墨西哥旅行的纪念。感谢泽哥、佳星和颖怡的同行，感谢热情的墨西哥人民。