Coco Passed Away
Feeling sad about Coco passing away.
2026 · May
Ep 176 mythic item
Ubuntu Server
Settled on Ubuntu as the production host for the Jonas sites — one server running the apps behind a reverse proxy.
Infra is described as Ansible playbooks so base setup, deploys, and rebuilds stay repeatable when migrating or standing up a new box.
Jonas Website Authentication Service
Started a shared login service for the Jonas sites — one place to sign in, so edu, homepage, and later apps don’t each keep their own accounts.
Apps stay public where they should; private materials stay behind roles decided per app. No passwords stored on the client sites.
Jonas Education Website
Started edu.jonasruilong.com as a personal lecture-notes library — Kanti Wettingen → ETH Zürich → Baruch
- Institution → term → course drill-down; file-based markdown in git
- FastAPI + Jinja2; math-first reading (KaTeX, plots, Mermaid)
- OAuth via shared auth when private materials need role gating
Achievements:
- First version of the education website is live
- Notes for Analysis 1&2, ODE/PDE course is uploaded and supports multiple graphs, formulas etc.
Jonas Homepage
Started jonasruilong.com as the personal hub — story and navigation into other apps.
Explored layout ideas and chose a scroll-driven 2.5D “scroll opera”:
Welcome first, themed worlds as portals, Dock later.
- Astro + React for the interactive front end.
- Thin Python backend to serve the build
Achievements:
- First version of the homepage is live
- Good visual design for the homepage
- 3D render of a Dragon, so learnt a bit of Blender as well
- Cut scene between Welcome and EDU
- Heart for Pau
Talent and Hard Work
Dark Theme Research
Perceptual Neutral:
hue 245, chroma 0.002. Tiny cool tint to counter the warm bias most monitors have at low brightness. Apple-HIG trick — looks like pure gray on your screen.
PDE with Financial Engineering Applications
Lecture 1
- Introduction to ODE
- First-order ODE
- Separable ODE
- First-order linear ODE
- Default probabilities and hazard rate
- Exact ODEs
Interview:
Sanity check at the end is useful, you can tell the interviewer that you will do a sanity check
Did more but not going to put it here for now, as I already have it on my edu site
Financial Economics
Lec 10
CAPM: combination of risk free asset and tangent portfolio
Sharpe Ratio: Slope of riskfree + risky of efficient frontier = sharpe ratio
Tangent Portfolio has the highest sharpe ratio among risky assets