Deemo(Yizhou) Chen's Observatory


Site Major UPDATE*


Hi, This site has been operating for almost 5 years, and I’ve moved to the United States for College. The original site was hosted on a cloud server in Hong Kong, and now the new Hosting Service would be provided by Vultr at Silicon Valley. Meanwhile, I added two domains: and, both of them would be redirected to the master domain In the near...

Machine Learning Notes III


*This note is still open Machine Learning Notes I Machine Learning Notes II The Primal Question of Optimization For a general optimization problem, it usually could be rewritten as maximizing or minimizing a certain function with several constrictions. For example, maybe you want the optimized value non-negative. The most basic form of such is called the primal question which looks like this: And...

Machine Learning Notes II


Link to Machine Learning Notes I The least squares estimates of α and β For simple linear regression: we have: Linear Regression way We can all use the NN method to solve the regression problem but that leads to being nearly impossible to locate exactly which layer foreshadows which feature of the data. Thus, maybe the better way is to upscale the dimension of the linear regression method. That...

Bayes’ Rule


When I was in the high school learning about AP statistics I learned the formula: , Which able to be transformed as: is called “Conditional probability” which pretty much self-explained itself. For which I only knew the meaning of each element but not the whole idea, what I do is just plug in numbers, because it is kinda abstract to understand from itself: “The probability of...

My Graduation Speech


My dear teachers and parents, my lovely fellow class of 2020, it’s my great honor here to speak as a student representative, and thank you for choosing to join today’s graduation ceremony. You know, it might be the last time you see most of your surroundings, your classmates, your teacher. I mean, you would not even get in touch with them anymore. Maybe in the near future, you would call them...

Machine Learning Notes I


Lately, I was into the studying process of machine learning, and outputting(taking notes) is a vital step of it. Here, I am using Andrew Ng’s Stanford Machine Learning course in Coursera with the language of MATLAB. So the rest of the code I will write in this post by default are based on MATLAB. What is ML? “A computer program is said to learn from experience E with respect to some...

Where We From and Where Human Will Go


There was a big explosion, the time be created, the world was created; the particles appear, they make impacts on each other by forces, they interact with each other–then the future be determined–just like begin a game of billiard, at the moment the stick hit the first ball, then all the future is determined. If the initial factors of the universe are typed into a supercomputer, then...

The Green Night


It’s summer night, hot, but cold inside. The castle is full of people—women and knights. At that time, I could be the youngest one there. “What is a real knight?” the King Arthur suddenly looking at me with his deep green eyes. I did not except that, but as quick as it is my nature, I response words that I called out for thousands of times when I was an initiate knight: “Honor, wisdom, humble...

Deemo(Yizhou) Chen's Observatory