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🔗 Biography 🔗 Computing 🔗 Biography/science and academia 🔗 Computing/Software 🔗 Computing/Free and open-source software 🔗 Computing/Amiga 🔗 Open

Fred Fish (November 4, 1952 – April 20, 2007) was a computer programmer notable for work on the GNU Debugger and his series of freeware disks for the Amiga.

The Amiga Library Disks – colloquially referred to as Fish Disks (a term coined by Perry Kivolowitz at a Jersey Amiga User Group meeting) – became the first national rallying point, a sort of early postal system. Fish would distribute his disks around the world in time for regional and local user group meetings, which in turn duplicated them for local distribution. Typically, only the cost of materials changed hands. The Fish Disk series ran from 1986 to 1994. In it, one can chart the growing sophistication of Amiga software and see the emergence of many software trends.

The Fish Disks were distributed at computer stores and Amiga enthusiast clubs. Contributors submitted applications and source code and the best of these each month were assembled and released as a diskette. Since the Internet was not yet in popular usage outside military and university circles, this was a primary way for enthusiasts to share work and ideas. He also initiated the "GeekGadgets" project, a GNU standard environment for AmigaOS and BeOS.

Fish worked for Cygnus Solutions in the 1990s before he left for Be Inc. in 1998.

In 1978, he self-published User Survival Guide for TI-58/59 Master Library, which was advertised in enthusiast newsletters covering the TI-59 programmable calculator.

🔗 Computing 🔗 Computing/Software 🔗 Writing systems 🔗 Typography

A bidirectional text contains both text directionalities, right-to-left (RTL or dextrosinistral) and left-to-right (LTR or sinistrodextral). It generally involves text containing different types of alphabets, but may also refer to boustrophedon, which is changing text direction in each row.

Some writing systems including the Arabic and Hebrew scripts or derived systems such as the Persian, Urdu, and Yiddish scripts, are written in a form known as right-to-left (RTL), in which writing begins at the right-hand side of a page and concludes at the left-hand side. This is different from the left-to-right (LTR) direction used by the dominant Latin script. When LTR text is mixed with RTL in the same paragraph, each type of text is written in its own direction, which is known as bidirectional text. This can get rather complex when multiple levels of quotation are used.

Many computer programs fail to display bidirectional text correctly. For example, the Hebrew name Sarah (שרה) is spelled: sin (ש) (which appears rightmost), then resh (ר), and finally heh (ה) (which should appear leftmost).

Note: Some web browsers may display the Hebrew text in this article in the opposite direction.

🔗 Biography

Jonathan Gillette, known by the pseudonym why the lucky stiff (often abbreviated as _why), is a writer, cartoonist, artist, and programmer notable for his work with the Ruby programming language. Annie Lowrey described him as "one of the most unusual, and beloved, computer programmers" in the world. Along with Yukihiro Matsumoto and David Heinemeier Hansson, he was seen as one of the key figures in the Ruby community.

_why made a presentation enigmatically titled "A Starry Afternoon, a Sinking Symphony, and the Polo Champ Who Gave It All Up for No Reason Whatsoever" at the 2005 O'Reilly Open Source Convention. It explored how to teach programming and make the subject more appealing to adolescents. _why gave a presentation and performed with his band, the Thirsty Cups, at RailsConf in 2006.

On 19 August 2009, _why's accounts on Twitter and GitHub and his personally maintained websites went offline. Shortly before he disappeared, why the lucky stiff tweeted, "programming is rather thankless. u see your works become replaced by superior ones in a year. unable to run at all in a few more."

_why's colleagues have assembled collections of his writings and projects.

Later his website briefly went back online with a detailed explanation of his plans for the future.

🔗 Urban studies and planning 🔗 Horticulture and Gardening

A ha-ha (French: hâ-hâ or saut de loup) is a recessed landscape design element that creates a vertical barrier while preserving an uninterrupted view of the landscape beyond.

The design includes a turfed incline that slopes downward to a sharply vertical face (typically a masonry retaining wall). Ha-has are used in landscape design to prevent access to a garden, for example by grazing livestock, without obstructing views. In security design, the element is used to deter vehicular access to a site while minimizing visual obstruction.

The name "ha-ha" is thought to have stemmed from the exclamations of surprise by those coming across them, as the walls were intentionally designed so as not to be visible on the plane of the landscape.

🔗 Spaceflight 🔗 Physics 🔗 Rocketry

The Tsiolkovsky rocket equation, classical rocket equation, or ideal rocket equation is a mathematical equation that describes the motion of vehicles that follow the basic principle of a rocket: a device that can apply acceleration to itself using thrust by expelling part of its mass with high velocity can thereby move due to the conservation of momentum.

${\displaystyle \Delta v=v_{\text{e}}\ln {\frac {m_{0}}{m_{f}}}=I_{\text{sp}}g_{0}\ln {\frac {m_{0}}{m_{f}}}}$

where:

${\displaystyle \Delta v\ }$ is delta-v – the maximum change of velocity of the vehicle (with no external forces acting).

${\displaystyle m_{0}}$ is the initial total mass, including propellant, also known as wet mass.

${\displaystyle m_{f}}$ is the final total mass without propellant, also known as dry mass.

${\displaystyle v_{\text{e}}=I_{\text{sp}}g_{0}}$ is the effective exhaust velocity, where:

${\displaystyle I_{\text{sp}}}$ is the specific impulse in dimension of time.

${\displaystyle g_{0}}$ is standard gravity.

${\displaystyle \ln }$ is the natural logarithm function.

🔗 Mathematics 🔗 Statistics 🔗 Psychology

Accuracy and precision are two measures of observational error. Accuracy is how close a given set of measurements (observations or readings) are to their true value. Precision is how close the measurements are to each other.

The International Organization for Standardization (ISO) defines a related measure: trueness, "the closeness of agreement between the arithmetic mean of a large number of test results and the true or accepted reference value."

While precision is a description of random errors (a measure of statistical variability), accuracy has two different definitions:

1. More commonly, a description of systematic errors (a measure of statistical bias of a given measure of central tendency, such as the mean). In this definition of "accuracy", the concept is independent of "precision", so a particular set of data can be said to be accurate, precise, both, or neither. This concept corresponds to ISO's trueness.
2. A combination of both precision and trueness, accounting for the two types of observational error (random and systematic), so that high accuracy requires both high precision and high trueness. This usage corresponds to ISO's definition of accuracy (trueness and precision).

🔗 Mathematics

The ant on a rubber rope is a mathematical puzzle with a solution that appears counterintuitive or paradoxical. It is sometimes given as a worm, or inchworm, on a rubber or elastic band, but the principles of the puzzle remain the same.

The details of the puzzle can vary, but a typical form is as follows:

An ant starts to crawl along a taut rubber rope 1 km long at a speed of 1 cm per second (relative to the rubber it is crawling on). At the same time, the rope starts to stretch uniformly at a constant rate of 1 km per second, so that after 1 second it is 2 km long, after 2 seconds it is 3 km long, etc. Will the ant ever reach the end of the rope?

At first consideration it seems that the ant will never reach the end of the rope, but in fact it does. (In the form stated above, it would take 8.9×10⁴³⁴²¹ years.) Whatever the length of the rope and the relative speeds of the ant and the stretching, provided that the ant's speed and the stretching remain steady, the ant will always be able to reach the end given sufficient time. Once the ant has begun moving, the rubber rope is stretching both in front of and behind the ant, conserving the proportion of the rope already walked by the ant and enabling the ant to make continual progress.

🔗 Time 🔗 Switzerland

Swatch Internet Time (or .beat time) is a decimal time concept introduced in 1998 by the Swatch corporation as part of their marketing campaign for their line of "Beat" watches.

Instead of hours and minutes, the mean solar day is divided into 1000 parts called ".beats". Each .beat is equal to one decimal minute in the French Revolutionary decimal time system and lasts 1 minute and 26.4 seconds (86.4 seconds) in standard time. Times are notated as a 3-digit number out of 1000 after midnight. So, for example @248 would indicate a time 248 .beats after midnight representing ​²⁴⁸⁄₁₀₀₀ of a day, just over 5 hours and 57 minutes.

There are no time zones in Swatch Internet Time; instead, the new time scale of Biel Meantime (BMT) is used, based on Swatch's headquarters in Biel, Switzerland and equivalent to Central European Time, West Africa Time, and UTC+01. Unlike civil time in Switzerland and many other countries, Swatch Internet Time does not observe daylight saving time.

🔗 Mathematics

Toom–Cook, sometimes known as Toom-3, named after Andrei Toom, who introduced the new algorithm with its low complexity, and Stephen Cook, who cleaned the description of it, is a multiplication algorithm for large integers.

Given two large integers, a and b, Toom–Cook splits up a and b into k smaller parts each of length l, and performs operations on the parts. As k grows, one may combine many of the multiplication sub-operations, thus reducing the overall complexity of the algorithm. The multiplication sub-operations can then be computed recursively using Toom–Cook multiplication again, and so on. Although the terms "Toom-3" and "Toom–Cook" are sometimes incorrectly used interchangeably, Toom-3 is only a single instance of the Toom–Cook algorithm, where k = 3.

Toom-3 reduces 9 multiplications to 5, and runs in Θ(n^{log(5)/log(3)}) ≈ Θ(n^1.46). In general, Toom-k runs in Θ(c(k) n^e), where e = log(2k − 1) / log(k), n^e is the time spent on sub-multiplications, and c is the time spent on additions and multiplication by small constants. The Karatsuba algorithm is a special case of Toom–Cook, where the number is split into two smaller ones. It reduces 4 multiplications to 3 and so operates at Θ(n^{log(3)/log(2)}) ≈ Θ(n^1.58). Ordinary long multiplication is equivalent to Toom-1, with complexity Θ(n²).

Although the exponent e can be set arbitrarily close to 1 by increasing k, the function c unfortunately grows very rapidly. The growth rate for mixed-level Toom–Cook schemes was still an open research problem in 2005. An implementation described by Donald Knuth achieves the time complexity Θ(n 2^{√2 log n} log n).

Due to its overhead, Toom–Cook is slower than long multiplication with small numbers, and it is therefore typically used for intermediate-size multiplications, before the asymptotically faster Schönhage–Strassen algorithm (with complexity Θ(n log n log log n)) becomes practical.

Toom first described this algorithm in 1963, and Cook published an improved (asymptotically equivalent) algorithm in his PhD thesis in 1966.

🔗 Biography 🔗 Australia 🔗 Transport 🔗 Transport/Maritime 🔗 Australia/Australian maritime history 🔗 Australia/Western Australia 🔗 Australia/Australia, New Zealand and South Pacific military history

Frederick Benjamin "Ben" Carlin (27 July 1912 – 7 March 1981) was an Australian adventurer who was the first person to circumnavigate the world in an amphibious vehicle. Born in Northam, Western Australia, Carlin attended Guildford Grammar School in Perth, and later studied mining engineering at the Kalgoorlie School of Mines. After qualifying as an engineer, he worked on the Goldfields before in 1939 emigrating to China to work in a British coal mine. In the Second World War, Carlin was posted to the Indian Army Corps of Engineers, serving in India, Italy, and throughout the Middle East. After his discharge from service in 1946, he emigrated to the United States with his American wife, Elinore (née Arone).

Sparked by an idea he had had whilst in the military, Carlin proposed that the couple honeymoon by crossing the Atlantic Ocean in a modified Ford GPA (an amphibious version of the Ford GPW Jeep), which they named the Half-Safe. Beginning their trip in Montreal, Quebec, Canada, the Carlins finally completed the transatlantic crossing in 1951, after unsuccessful attempts. From there, they travelled to Europe, temporarily settling in Birmingham to raise more money. They resumed their journey in 1954, travelling overland through the Middle East before arriving in Calcutta. After a short fundraising trip to Australia, Carlin's wife left to return to the United States. He resumed the journey with new partners, travelling through South-East Asia and the Far East to the northern tip of Japan, and then to Alaska. After an extended tour through the United States and Canada, he and Half-Safe finally returned to Montreal, having travelled over 17,000 kilometres (11,000 mi) by sea and 62,000 kilometres (39,000 mi) by land during a ten-year journey. Following Carlin's death in 1981, Half-Safe was acquired by Guildford Grammar, his old school, where it remains on display.