Sekai 🌐 πŸ—Ί

Sekai is the kanji for δΈ–η•Œ, meaning “the world”. That’s a great word because of the scale it designates.

Deploy Hugo Theme exampleSite With Github Actions

Motivation To test PRs on the upstream of a Hugo theme by setting up a testing branch. Goal To deploy a forked GitHub repo for a Hugo theme with exampleSite to GitHub Pages using GitHub Actions. The whole article is based on my fork of Hugo Future Imperfect Slim. References GitHub Actions for Hugo A Stack Overflow question showing pwd in GitHub Actions A Hugo Discourse post about testing exampleSite Difficulties I had failed for about ten times before I got the job done. [Read More]

First Experience with ASP.NET Core MVC & PostgreSQL

Goal To build an ASP.NET Core 5 MVC web app linked with a PostgreSQL. Motivation SQL Server is proprietary. SQLite used in Microsoft’s ASP.NET Core 5 MVC tutorial isn’t made for web apps. MySQL doesn’t perform well with concurrent read-writes. It’s dual-licensed like GitLab. Some users find PostgreSQL cost-effective. Useful tutorials MS’s tutorial in item 2 above. Wes Doyle’s YouTube video goes through the steps MS’s tutorial for Razor Pages with EF Core migrations Steps Create a superuser in the database. [Read More]

Deleted Question on Semi-Simple and Projective but not Injective Module

A backup of a deleted PSQ : OP : irfanmat It has a detailed answer by Atticus Stonestrom. It’s pity that his post got deleted. As there’s no reason for undeletion, I’m posting it here so as to preserve the contents. Question body Is there a semi-simple and projective but not injective module? I will be glad if you help. Response(s) In the non-commutative case, the answer is yes. [Read More]

Another Math.SE Double Integral Using Polar Coordinate

I wanted to post the following answer to a question on double integral on Math.SE, but someone had submitted his work before I finished typing. As a result, I’m posting this on my personal blog. Let $r = \sqrt{x^2+4y^2}$ and $t = \begin{cases} \tan^{-1}(2y/x) &\text{ if } x > 0 \\ \pi/2 &\text{ if } x = 0. \end{cases}$ Then $\begin{cases} x &= r \cos t \\ y &= (r \sin t)/2 \end{cases}$ and $D = { (r,t) \mid r \ge 0, t \in [\pi/4, \pi/2] }$. [Read More]

Ways to Draw Diagrams Displayed on Math.SE

I wanted to start a meta question, but I don’t see a point of that after viewing some related posts listed at the end of the next subsection. Intended question You may vote on your preferred way. Ways Advantages Disadvantages AMScd supported on Math.SE for a long time no diagonal arrowssyntax less well-knownTwo-way arrows $\rightleftarrows$ look odd array supported on Math.SE for a long timeeasier syntaxwrite basic diagonal arrows like $\nearrow$ fine tuning spacing is harddiagonal arrows only work for neighboring nodes ASCIIFlow WYSIWYG interface lines are rendered as slashes in code TikZ well known syntaxcan draw pretty diagrams not supported on SE, need to import as picture others? [Read More]

Combat Procrastination

My notes for a YouTube video about procrastination on one hearing only. Why? Boring tasks. It’s necessary? Yes: Make it fun. Get a study partner. Find a more energetic time. No: Get rid of it. Surrounding environment. Identify someone who procrastinates in your circle of influence. Distance yourself from them, or Be aware of what their behavior. Perfectionism [Read More]

GIMP w'ont Start after Ubuntu Distro Upgrade

Problem After upgrading to Ubuntu 20.04 form 18.04, I wasn’t able to start GIMP 2.10. The message was in the same format as that in a related Ask Ubuntu question, except that the version numbers were greater. I attempted installing the package gegl, which was irrelavant to the problem. Analysis I found the answers mentioning the package libgegl helpful. $ dpkg -l | grep gegl ii gegl 0.4.22-3 amd64 Generic Graphics Library Test Program ii libgegl-0. [Read More]
Ubuntu  GIMP 

Recover Mysql Root Password

Just a little linklog to a relevant page on How to Forge. Root privileges are needed. Stop service: service mysql stop Start MySQL server w/o password: mysqld_safe --skip-grant-tables & Connect to CLI client as root: mysql -u root Reset root password. Here’s the syntax for β‰₯v.5.7.6. mysql> use mysql; mysql> SET PASSWORD FOR 'root'@'localhost' = PASSWORD("newpass"); mysql> flush privileges; mysql> quit Repeat step 1, or killall mysqld if it doesn’t work. [Read More]

Pandoc LaTeX Mermaid on GitLab CI

Goal To provide an open-source alternative to the Docker image escalope/pandoc-mermaid-plantuml, whose Dockerfile isn’t available. The rationale behind these difficult setup is simple: construct informative Mermaid diagram with intuitive Markdown syntax in an open-source and economic way. This newly constructed Docker image is entirely on GitLab. No Docker Hub account is needed. For sample usage, consult .gitlab-ci.yml in my test project. Difficulties issues raghur/mermaid-filter#51 and #52 issue gitlab-org/gitlab-runner#4566 Useful code/articles time-machine-project/requests-for-comments@470b0c5 Dockerfile Reduce Docker Image Sizes Using Alpine Best practices for building docker images with GitLab CI with the accompanying gist The code block in the highlighted comment in item 2 of the above section pandoc installation for Docker Sample Dockerfile for Alpine Linux in the troubleshooting of Puppeteer sc250024/docker-mermaid-cli@3c9ddb5 src/puppeteerConfigFile. [Read More]

Site Maintenance for Hugo v0.60

Background I lacked motivation to keep this tweaked theme up with Hugo’s development after last summer. When I came back yesterday, I saw that some pages using Font Awesome icons were broken. Apart from that, the ToC list level problem resurfaced. Fixed ToC The solution that I had adopted no longer worked. Luckily, some users provided a shorter code in the later discussions. The one from user501254 caught me. I first tried to copy his code into the partial layout for ToC. [Read More]