Personal Site of Andrei N. Ciobanu

Or The solvers might feel lost.

I always knew it was inevitable that I’d build my own RSS reader.

This article should be read with the opening scene of Westworld in mind.

Scroll inside the stage with the mouse wheel or with your finger.

While reading some classic poetry, I accidentally found Samuel Taylor Coleridge’s A Mathematical Problem: On a given finite line Which must no way incline; To describe an equi– –lateral Tri– –A, N, G, L, E.

Weekend articles should be lighter and fun.

A silly story is easier to remember This article is about “a vision” that I have.

…symmetry isn’t just a preference for “pretty” shapes.

Some jokes write themselves.

These thoughts were drafted during a night, a few months ago.

It’s 2026, and my interest in writing was at a new all-time low.

Contents Disclaimer Introduction Inequations vs.

How it started This story began, unexpectedly, on Facebook in a math-focused group.

When I was a young student (around 12), my math teacher had a unique requirement: students had to not only solve math problems but also compose them.

In the landscape of the Romanian 10th-grade Math Olympiad, logarithms are a distinct and recurring theme.

System Log: Sinusoidal Tetris Let's play Tetris, but with a twist.

This article will be part of an extensive series in which I plan to explore various aspects of Fourier Mathematics.

Before we begin, I’d like to clarify that the project ideas I am about to suggest are mainly intended for those who are interested in exploring new areas of knowledge.

Intro This article is a continuation of my previous selection of non-trivial algebra problems from the Romanian Math Olympiad for high-school students.

In this short article, I will discuss a cute mathematical problem that I discovered while reading “Polya’s Footsteps: Miscellaneous Mathematical Expositions” by the Canadian mathematician Ross Honsberger.

Introduction This is a “follow-up” to the previous article: “The math exams of my life”, as some readers were curious to see some examples of Math Olympiad exercises.

The system is flawed The Romanian public education system, which, by the way, is free for everyone (Universities included), has its flaws.

There’s this famous video on YouTube featuring Richard Feynman and a reporter.

This post is satire.

Contents Introduction Number systems A certain symmetry and patterns Numbers and Data Types in C Transforming numbers from decimal to other number systems (binary, hexadecimal, etc.)

I recently stumbled upon an article about the Weierstrass Function, which led me to another article about Pathological Objects in mathematics—meaning functions, numbers, etc., that have deviant, irregular, or counterintuitive properties.

… actually you can use only 2, but this will make your life a little more miserable.

Contents Introduction The code Running the sample blog Adding a new blog post to the sample blog How everything works The model and a neat pre-processor trick The server Conclusions Discussion Introduction Recently, while browsing lobste.rs, I had the cha…

The current article won’t be an exhaustive technical analysis of Gradle but more like a spontaneous rant.

This article assumes the reader is already familiar with the C programming language and some basic concepts concerning hash functions.

This article explains a straightforward approach for generating Perfect Hash Functions, and using them in tandem with a Map<K,V> implementation called ReadOnlyMap<K,V>.

The book Life of Pi, written in 2001 by Canadian author Yann Martel, tells the story of a young Indian boy fascinated by philosophy, spirituality, and religious syncretism from an early age.

This tutorial is intended for intermediate C developers who want to get some coding practice and, in the process, gain valuable insights into low-level programming and how (some) Virtual Machines operate under the hood.

The intended audience for this article is undergrad students who already have a good grasp of Java, or seasoned Java developers who would like to explore an in-depth analysis of various hash table implementations that use Open Addressing.

Table of contents Contents Table of contents Code Introduction C++ (unordered_map) Java (HashMap) Python (dict) Performance: Why Size Doesn’t Matter Hash Functions Hash Collisions What makes a “Good” Hash Function?

Contents Introduction Working with an UCI-enabled engine from the command line Installing Stockfish (and Leela Zero) Listing supported options Changing an option Analyzing a position Writing the Java UCI Client library Opening and closing the engine proce…

mapneat is a library I’ve written a long time ago.

mapneat is a library I’ve written a long time ago.

Contents Introduction Think of matrices as functions Matrix transformations Linear Transformations Eigenvalues and Eigenvectors Why are they “special”?

Contents Introduction Using QR Decomposition to Determine Eigenvalues Implementing the Naive Algorithm Improving the Algorithm: Practical QR with Shifts More Improvements: The Hessenberg Form But what about the Eigenvectors?

Contents Disclaimer Math, math The Library Source Code The data: nml_matrix Breakdown of the Structure A Note on Memory Layout Allocating / De-allocating memory for the nml_mat matrix Implementation: nml_mat_new() Implementation: nml_mat_free() Expanding…

pysert (lowercase ‘p’) is a python utility designed to generate random SQL INSERT statements from predefined templates.

Java annotations are syntactic meta-information that can be added to your source code.

Even though Java 7 introduced a low-level API to watch for file system changes (see the article here), you also have the option of using the Commons IO library from the Apache Foundation, specifically the org.apache.commons.io.monitor package.

A list of best practices for writing bash scripts: Use a portable shebang In computing, a shebang is the character sequence consisting of the characters number sign and exclamation mark (#!)

Contents Introduction The Binary Heap Why use a Heap?

Contents Introduction The Algorithm Implementations Scala Python Haskell Introduction One of the earlier challenges from Programming Praxis was the RPN Calculator.

Introduction If you’ve ever tried to write your own calculator, you’ve probably needed a way to convert mathematical expressions written in the usual infix notation into Reverse Polish Notation (RPN).

Update (2026): This was the first 'real article' I ever wrote.

My first blog post, in which I am writing Hello World!.