Link Archive

This page explains the design and implementation of operations on big (modular) integers, used for RSA and generic elliptic curve computations.

This article walks through the components of a modern LZ compressor. It's amazing how rich and deep the compression field is. If you enjoy algorithms and data structures, there are not too many better places to play. I hope you enjoy reading it as much as I enjoyed writing it!

By the end, we will have a compressor that can beat gzip while decompressing at almost the same speed — in less than 1000 lines. You can find the source for the article at https://github.com/glinscott/linzip2.

The Apollo Guidance Computer (AGC) provided guidance, navigation and control onboard the Apollo flights to the Moon. This historic computer was one of the first to use integrated circuits, containing just two types of ICs: a 3-input NOR gate for the logic circuitry and a sense amplifier IC for the memory. It also used numerous analog circuits built from discrete components using unusual cordwood construction.

magine that you have attached a pencil to a pendulum so that it brushes across a piece of paper as the pendulum swings back and forth. When the pendulum finishes swinging you will end up with a single straight line drawn on your paper – very dull indeed! Now imagine further that you somehow manage to connect a second pendulum to your pencil which oscillates at right angles to the first. The resulting drawing might look something like the image below. If your imagination fails you (or if my explanation isn’t up to the job) then you can see a video of the set up I am trying to describe by clicking here.

Strange Attractors are plots of relatively simple formulas. They are created by repeating (or iterating) a formula over and over again and using the results at each iteration to plot a point. The result of each iteration is fed back into the equation. After millions of points have been plotted fractal structures appear. The repeated points fall within a basin of attraction (they are attracted to the points that make up these shapes).

 

But the fix is easy and there’s no addons required.

1. Navigate to about:config (in Firefox’s URL bar)
2. Change the value of the following two properties to 0:
   • mousewheel.with_control.action
   • mousewheel.with_meta.action

 

In firefox 63 the autoplay preferences are reorganised in preparation for this feature shipping out of the box in one of the upcoming versions. in about:config you can set media.autoplay.default to 1 in order to block automatic playback on all pages or set it to 2 to decide on a per domain basis.

Observers of yesterday’s lunar eclipse were blessed with the first known sighting of a meteorite impact during such an event.

Every molecule of water on the Earth and inside you or any other living thing has existed for billions of years. After it came to Earth, that water has been cycling through rocks, air, animals, plants, and back again. Each molecule has been on an incredible voyage before coming to you. At some point, the water inside you would have been inside dinosaurs, bacteria, the oceans, storm clouds, the polar ice caps, and much more.

The Intel 80386 is the next step in the evolution of the processor series that started with the Intel 8086 (which was itself inspired by the Intel 8080, which was in turn inspired by the Intel 8008). Even at this early stage, it had a long history, which helps to explain many of its strange corners.

As with all the processor retrospective series, I'm going to focus on how Windows NT used the Intel 80386 in user mode because the original audience for all of these discussions was user-mode developers trying to get up to speed debugging their programs. Normally, this means that I omit instructions that you are unlikely to see in compiler-generated code. However, I'll set aside a day to cover some of the legacy instructions that are functional but not used in practice.

Nancy by Olivia Jaimes for January 20, 2019 https://www.gocomics.com/nancy 

10 PRINT is a book about a one-line Commodore 64 BASIC program, published in November 2012. Book purchases support the nonprofit organizations The Electronic Literature Organization (to which all royalties are being donated) and The MIT Press, the book's publisher.

A graphical technique for the display of the Lyapunov exponent as a function of control parameters in one-dimensional maps is used to identify coexistence of attractors, superstable curves, highly interleaved basins of attraction in phase space, and highly interleaved regions with different oscillatory modes in parameter space. Furthermore, this technique reveals dramatic' changes of dynamic behavior due to small discontinuities at the maximum of the maps.

This is an online preview of the book “Fundamentals of Data Visualization” to be published with O’Reilly Media, Inc.

The book is meant as a guide to making visualizations that accurately reflect the data, tell a story, and look professional. It has grown out of my experience of working with students and postdocs in my laboratory on thousands of data visualizations. Over the years, I have noticed that the same issues arise over and over. I have attempted to collect my accumulated knowledge from these interactions in the form of this book.

The Feynman trap—ransacking data for patterns without any preconceived idea of what one is looking for—is the Achilles heel of studies based on data mining. Finding something unusual or surprising after it has already occurred is neither unusual nor surprising. Patterns are sure to be found, and are likely to be misleading, absurd, or worse.

I've always been fascinated with patterns. It doesn't really matter what kind of patterns; I've played with networks, leaves and leaf venation, branches, lightning, flocking, tracing outlines of shapes, river formation, rock sediments, landscapes, slime mold, lichens,reaction-diffusion, cellular automaton, some fractals, and a few other things. I think what I enjoy the most is how complex and intricate results you can get from a set of simple rules.

At ITP, I teach a course entitled Introduction to Computational Media. In this course, the students learn the basics of programming (variables, conditionals, loops, objects, arrays) as well as a survey of applications related to making interactive projects (images, pixels, computer vision, networking, data, 3D). The course mostly follows the material found in my intro book Learning Processing; in many ways, The Nature of Code serves as a follow-up. Once you’ve learned the basics and seen an array of applications, your next step might be to delve deeply into a particular area. For example, you could focus on computer vision (and read a book like Greg Borenstein’s Making Things See). In the most basic sense, this book is one possible next step in a world of many. It picks up exactly where Learning Processingleaves off, demonstrating more advanced programming techniques with Processing that focus on algorithms and simulation.

This web page contains a free electronic version of my (soon to be) self-published textbook Algorithms, along with other lecture notes I have written for various theoretical computer science classes at the University of Illinois, Urbana-Champaign since 1998.