All streams

Faced with the situation when calling Mono::block leads to deadlock - in debug I can just see how it stands on Unsafe::park and no more movement at all.

V. Komen, I. Tikhonenkov

In the previous post we've considered a model example of a motion of a free particle within a uniform gravitation field where a coupling to the field is defined by an observed inertion mass (see eq. (2) in https://habr.com/en/articles/739714/). The equation of motion was:

Yes, we need IT

The foundation of our civilization is tools. We didn't just evolve to a state that allowed us to use them, we began to improve them ourselves. The tools are becoming more intricate, more efficient and more perfect. It can be a hammer, an industrial robot, or a monetary relationship. 

Some of our tools are difficult to grasp or comprehend, they are more like an element or a subject of study: the Internet, the media, the transport system. It is even difficult to call them tools, rather it is a reflection of our activities. For simplicity, we will call everything that people do with their own hands a tool, meaning that they speed us up, make our life easier and more comfortable.

Why do we need tools? On the one hand, they help to solve emerging problems, on the other hand, they raise the standard of living. We enjoy creating tools. I would say it's one of our instincts. 

For the functioning of our body, we need some amount of mathematics. The processes in our head reflect this math into our language. We can write the language in the form of symbols. With the help of symbols, we can convey the discovery of one person to another or a thousand others. This allows us to build more and more complex tools. And most importantly, we really like it: the brain encourages us every time we invent or achieve something. Therefore, our tools are developing with us. The mechanisms of their development and improvement are sewn into us.

Migratory birds fly south in autumn, north in spring. It's their instinct. Ants build an anthill — it's their instinct. If people are left in satiety and peace, they begin to encode secret messages in the Bible, create complex etiquette, form mathematics, experiment with materials.

1 Playing Diplomacy

1.1 What this work is about

1.2 A puzzle for the talented and brave (Eccentrics are welcome: ?)

Hello, everyone! I’m Yaroslav Fomenko, Doubletapp iOS-developer. Since the end of May, my department colleague and I have been working on implementation, improvement, and scaling of CI/CD for our projects. In this article, we want to share a guide on preparing the Xcode project and setting up runners, scripts, and configs, as well as explain how CI/CD helps us.

To learn how and why we decided to use a Mac mini for CI/CD, click here.

Hey, Habr! I’m Yaroslav Fomenko, Doubletapp iOS-developer. After our IOS department deployed our CI/CD on a Mac Mini, we got an idea of scaling and encapsulating it. So we started researching ways to do it. First we thought of Docker, but there was neither enough info about it nor any other possible ways. In this article, we’ll look at all possible solutions we found for the deployment of Gitlab CI/CD on a device and in the cloud.

Hi Everyone,

I would like to draw your attention to some key insights from two comprehensive reports, shedding light on the importance of fraud prevention as a burgeoning field with substantial job prospects. The original reports can be accessed through the link provided at the end of this message.

Firstly, let's consider a couple of significant events from the previous year that remain highly relevant. Retail e-commerce sales surged to a staggering $5 trillion, with projections indicating a further increase to $8 trillion by 2026. Furthermore, the percentage of shoppers making cross-border purchases rose from 69% in 2019 to an impressive 76%.

These statistics affirm that online shopping is not a passing trend, as consumers are willing to make purchases from international vendors, even if it means enduring longer delivery times in exchange for lower prices. From a fraud prevention perspective, this highlights the escalating number of non-domestic payments and the rise in the use of lost or stolen cards for purchasing goods that can be resold in the future. Notably, refund fraud is becoming increasingly prevalent. However, many businesses have adapted their protocols to accommodate these emerging challenges. One such positive development is the gradual disappearance of restrictions on using payment methods that do not match the account country.

As cross-border purchases continue to proliferate, alternative payment methods are also on the rise. Current global statistics indicate that an average of four payment options are now available on merchant platforms. Additionally, open banking payment transactions are projected to surpass $330 billion globally by 2027, leading to a greater diversity of alternative payment methods. As companies embrace these methods, they are also becoming more aware of the associated risks. For instance, direct banking payment methods present unique challenges as they lack refund capabilities, while Buy Now Pay Later (BNPL) options introduce their own set of risks.

Experiments on the Torus

Not long ago, I started my personal blog. Instead of opting for the traditional route of using the popular WordPress CMS for blogs, I decided to embrace new technologies. My choice landed on Next.js and a NoSQL-type database.

Uniform gravity, can it exist?

1. The motion of a free particle-like cat

V. Komen, I. Tikhonenkov

Good morning! You've woke up. Having prepared coffee and toasts of bread you are drifting from a kitchen to a table before a large wall TV. The left hand keeps a small plate with toasts and the right one controls coffee level within your beloved mug. The life is plotted out for ten seconds to come. But Ervin is already worried that you, as usual, made conspiracy and decided not to share your breakfast with him. So the damned cat thrusts himself across you pass, hits your legs. By the next moment the plate, toasts and the mug are falling. And – yes! All those precious things reached a floor level by the same time. Physics...It's how it shows up, unexpected. And we used to identify ourselves as physicists. The unexpected thing is that we still do. It's whence our motivation originates. We cannot pass by any falling objects quietly.

1. About this series of articles

1.1 Central result

Brief problem formulation

The program accepts as input the absolute path to the image in the bmp extension and the path where you save the result of the work. Then, it rotates the image by 90 degrees counterclockwise. Afterwards, the program saves the new image.

The program is executed on C.

The end of the March Commitfest concludes the acceptance of patches for PostgreSQL 16. Let’s take a look at some exciting new updates it introduced.

I hope that this review together with the previous articles in the series (2022-07, 2022-09, 2022-11, 2023-01) will give you a coherent idea of the new features of PostgreSQL 16.

Explaining main algorithm.

For a while I’ve been thinking of writing a scientific article. I wanted it to have certain utility.

Morse code is binary: it takes only two values – either dot (short) or hyphen (long). I figured out that short (s) can stand for two-eye blinking whilst long (l) can indicate left-eye blinking. Another question emerged: how to understand when does one-symbol recording stop?

Empty space between two symbols can be presented by right-eye blinking – r. If I input singly symbol of short (dot) and long (hyphen), I will blink my right eye once to indicate the space between two symbols.

To separate independent words, one has to blink her right eye twice and get rr.

Hence, I have collected an ordered set of symbols – r, l, s, - that can be converted into a full-fledged text. Once I accomplish the transformation, I get an answer.

There are such types in Java - called "Generics".
And the point here is that there is a convention for naming generic type parameters WITH ONE CAPITAL LETTER.

But we have found much more readable approach!

The most important stage in the data science process is feature engineering, which entails turning raw data into useful features that might enhance the performance of machine learning models. It calls for creativity, data-driven thinking, and domain expertise. Data scientists can improve the prediction capability of their models and find hidden patterns in the data by choosing, combining, and inventing relevant features. Handling missing data, scaling features, encoding categorical variables, constructing interaction terms, and other procedures are examples of feature engineering techniques. The best practises involve investigating the data, testing and improving features iteratively, and applying domain knowledge to draw out important information. The accuracy and effectiveness of machine learning models are significantly influenced by effective feature engineering.

I explain experimental results of Bell’s Theorem by superdeterminism. I follow with insights into how such a universe may arise and be compatible with the subjective experience of free will.

One of the common tasks that both beginners and experienced game designers face is describing a large amount of content to pass its parameters to the engine. This is not an easy task, given that it is very difficult to find materials on the technical aspects of game design. Well, let’s figure out how to transfer data to the engine.