## Latest post

Jul 25, 2024, 01:46:46

After giving some thoughts, I think something like GitHub issues can be the ultimate form of a #socialmedia platform. One can conveniently refer to other issues using just owner/repo and issue number. One can use issue templates. One can use Markdown as well as inserting multimedia contents in comments. One can react with an emoji. These features easily beat Reddit and Mastodon. It only misses normal social platform features like exploration and tagging.

## Articles

• ### Drawing a heart using Joukowsky transformation

Joukowsky transformation of a circle centered at $\left(1,1\right)$ of radius $1$ is a curve resembling a heart.

• ### Generalization of Euler–Lagrange equation

We may generalize Euler–Lagrange equation to higher dimensional optimization problems: find a function defined inside a region to extremize a functional defined as an integral over that region, with the constraint that the value of the function is fixed on the boundary of the region.

• ### View of the world (physically rather than philosophically)

The view of the world… Physically! In this article, I tried to use mathematical language to describe models of the physical world. A view of the world should include: a space (actually spacetime) with some mathematical structure on it (whose points are events in the world), a symmetry principle describing the symmetry of the world, and a motion law to describe the physics and dynamics of the world. This article proposed models for Galilean, Einsteinian, and even Aristotelian worlds. Can you come up with even other worlds?

• ### Simulating a mechanical system using rpg_core.js

Continuing my last work of simulating a mechanical system using RGSS3, I made a new version using rpg_core.js, the game scripting system shipped with RPG Maker MV. This version is live on web!

• ### Simulating a mechanical system using RGSS3

Hamiltonian mechanics gives us a good way to simulate mechanical systems as long as we can get its Hamiltonian and its initial conditions. I implemented this simulation in RGSS3, the game scripting system shipped with RPG Maker VX Ace.

• ### Writing a DSL with commands split by space

DSL means domain-specific language. Ruby is a powerful script language in terms of building DSLs (as sublanguages of Ruby). In this article, I implemented my idea of a DSL with commands split by space. For example, you may just write a b c to run the commands a, b, and c one after another! This trick is heavily applied in my project alda-rb. How do I achieve this?

• ### Running Jekyll myself

I have got tired of letting GitHub Pages to run Jekyll for me. I cannot use custom plugins! I decide to run Jekyll myself and push the built result to GitHub repo. I wrote a script to do this.

• ### Algebraic structure of chemicals

Regarding balancing chemical equations, actually we are trying to find a non-trivial linear combination of some chemicals to get zero. The interesting thing is that the coefficients can only be integers ($\mathbb Z$), which is not a field, so the algebraic structure of chemicals is not linear space. They actually live in a free $\mathbb Z$-module. See how I formalize this idea in mathematical language.

• ### The concentration change of gas in reversible reactions

A reversible elementary reaction takes place inside a closed, highly thermally conductive container of constant volume, whose reactants are all gases. Given the reaction equations and the reaction rate constants, a natural question to ask is how the concentration of each gas changes w.r.t. time. In this article, I will answer this question by proposing a general approach to solve it.

• ### Snippet: O, ’tis too true!

O, ’tis too true!