The Theoretical Physics Reference is an attempt to derive all theoretical physics equations (that are ever needed for applications) from the general and special relativity and the standard model of particle physics.

The goals are:

   All calculations are very explicit, with no intermediate steps left out.
   Start from the most general (and correct) physical theories (general relativity or standard model) and derive the specialized equations from them (e.g. the Schrödinger equation).
   Math is developed in the math section (not in the physics section).
   Theory should be presented as short and as explicitly as possible. Then there should be arbitrary number of examples, to show how the theory is used.
   There should be just one notation used throughout the book.
   It should serve as a reference to any physics equation (exact derivation where it comes from) and the reader should be able to understand how things work from this book, and be ready to understand specialized literature.

TinyScheme is a lightweight Scheme interpreter that implements as large a subset of R5RS as was possible without getting very large and complicated. It is meant to be used as an embedded scripting interpreter for other programs. As such, it does not offer IDEs or extensive toolkits although it does sport a small top-level loop, included conditionally. A lot of functionality in TinyScheme is included conditionally, to allow developers freedom in balancing features and footprint.

we're a loose association of like-minded tilde communities. if you're interested in learning about *nix (linux, unix, bsd, etc) come check out our member tildes and sign up!
member status in the tildeverse mainly involves some level of engagement or presence on irc; all other systems are independent.

Package, dependency and environment management for any language—Python, R, Ruby, Lua, Scala, Java, JavaScript, C/ C++, FORTRAN, and more.

Conda is an open source package management system and environment management system that runs on Windows, macOS and Linux. Conda quickly installs, runs and updates packages and their dependencies. Conda easily creates, saves, loads and switches between environments on your local computer. It was created for Python programs, but it can package and distribute software for any language.

Lzip is a lossless data compressor with a user interface similar to the one of gzip or bzip2. Lzip can compress about as fast as gzip (lzip -0) or compress most files more than bzip2 (lzip -9). Decompression speed is intermediate between gzip and bzip2. Lzip is better than gzip and bzip2 from a data recovery perspective. Lzip has been designed, written and tested with great care to replace gzip and bzip2 as the standard general-purpose compressed format for unix-like systems.
The lzip file format is designed for data sharing and long-term archiving, taking into account both data integrity and decoder availability:
- The lzip format provides very safe integrity checking and some data recovery means. The lziprecover program can repair bit flip errors (one of the most common forms of data corruption) in lzip files, and provides data recovery capabilities, including error-checked merging of damaged copies of a file.
- The lzip format is as simple as possible (but not simpler). The lzip manual provides the source code of a simple decompressor along with a detailed explanation of how it works, so that with the only help of the lzip manual it would be possible for a digital archaeologist to extract the data from a lzip file long after quantum computers eventually render LZMA obsolete.
- Additionally the lzip reference implementation is copylefted, which guarantees that it will remain free forever.
The suffix .lz is used for files compressed with lzip.

See https://lists.dyne.org/lurker/message/20181020.205455.fbab5607.en.html for negative claims about Lzip.

Extract LaTeX from PDFs or handwritten notes in seconds just by taking a screenshot.

Download Snip for desktop and start saving time.

Free for 50 snips/month, $4.99/month for unlimited personal version.

Found via https://github.com/jethrokuan/mathpix.el, an Emacs interface to Mathpix.

CurrentRanger is a nanoAmp current meter featuring auto-ranging, uni/bi-directional modes, Bluetooth data logging options and more.

It is a highly hackable and affordable ultra low-burden-voltage ammeter, appropriate for hobby and professional use where capturing fast current transients and measurement precision are important.

You can simply program an Attiny85 via the audio output of a PC, Smartphone or audio-player.

Only a low-part count circuit is needed.

The bootloader presented here has the following features:
   low memory footprint: ~1KB
   [full Arduino IDE integration] (https://github.com/8BitMixtape/8Bit-Mixtape-NEO/wiki/3_3-IDE-integration)
   automatic Baudrate detection and callibration
   very simple circuit: two 10 k resistors and a 100 nF capacitor are needed to connect the microcontroller to the audio output of the PC or audio player
   one pin for data transmission is needed
   an optional led indicator, needs an extra pin, for the state of the boot loader
   as hex/binary to wav converter, programmed in java, is also available. It works on win and linux

Review of
Eyles, Don. Sunburst and Luminary. Boston: Fort Point Press, 2018. ISBN 978-0-9863859-3-3.
http://www.sunburstandluminary.com/SLhome.html

The next blog entry is interesting as well.
https://www.fourmilab.ch/fourmilog/archives/2019-11/001848.html
Crossfield, Albert Scott and Clay Blair. Always Another Dawn. Seattle, CreateSpace, [1960] 2018. ISBN 978-1-7219-0050-3.

Brief description of a failed attempt to install the virtual AGC
from https://www.ibiblio.org/apollo/ on a Raspberry π 4 running Raspian.