due to an eclipsing companion then this body would have to be much larger The image was taken by the ROSAT spacecraft and is courtesy of the Max Planck Institute. The star stays at its faintest value for two hours centered on the time of mid-eclipse. By Mission | PUNCH(3) sends output to the teleprinter rather than the tape punch. It is only smaller because it dumped a lot of its mass onto the younger star, making it more massive and subsequently to look beyond it's years. Algol (Beta Persei) seems to wink slowly, fading for almost 5 This month's Variable Star of the Month was prepared by Aaron Price. Elliott Algol used different characters for "open-string-quote" and "close-string-quote": Here is a version for the Elliott 803 Algol (A104) The standard Elliott 803 used 5 hole paper tape and thus only had upper case. Good comparison stars are nearby Gamma Andromedae (magnitude +2.2) to Algol’s west, and Epsilon Persei (magnitude +2.9) to its east. J. The report was translated into Russian, German, French, and Bulgarian, and allowed programming in languages with larger character sets, e.g., Cyrillic alphabet of the Soviet BESM-4. Unlike eclipsing binaries, the other two types of variable stars are intrinsically variable—that is to say, their own output of radiant energy fluctuates with time. in brightness. The open and close quote characters were represented using '(' and ')' and spaces by %.[22]. [20] Think of passing a pointer to swap(i, A[i]) in to a function. One of the reasons for this is that it is a star which can be observed with the unaided eye. This is known as stropping. ALGOL is a family of imperative computer programming languages originally developed in 1958. Algol’s name derives from the Arabic Al Ra’s al Ghul, “The Demon’s Head”, and in Greek mythology it represents the head of Medusa held by Perseus. The latter is still used for Unisys MCP system software. Because the Beta Persei system has a total mass of 5.8 solar masses, the system’s gravity may have disrupted the Oort cloud at its closest approach, possibly deflecting numerous comets into the inner solar system. Homer wrote of Algol in the Iliad: "...the Gorgon's head, a ghastly sight, deformed and dreadful, and a sight of woe". There is also a shallow secondary eclipse when the B8V star passes in front of the K2IV star. • May 16 – 14:40 UT again. More Info The text below was written by Dr. John R. Percy, former AAVSO president, and Dr. Janet A. Mattei, AAVSO director. John Backus developed the Backus normal form method of describing programming languages specifically for ALGOL 58. Another reason is because it has a relatively short period of less than three days. The above light curve is based upon observations of Algol made and submitted by John Isles. ALGOL 68 was defined using a two-level grammar formalism invented by Adriaan van Wijngaarden and which bears his name. A light curve is a plot showing the brightness variation of a sourcewith time. Variable stars may be classified into three broad types according to the origin and nature of their variability: (1) eclipsing, (2) pulsating, and (3) explosive. ALGOL 60 as officially defined had no I/O facilities; implementations defined their own in ways that were rarely compatible with each other. These became available in the mid-1960s while ALGOL 68 was being drafted. For example, without specifying the parameters as value or reference, it is impossible to develop a procedure that will swap the values of two parameters if the actual parameters that are passed in are an integer variable and an array that is indexed by that same integer variable. ££L?? There is a very faint third star in the system. (Question Mark) for close quote. The earliest known maligning of this star is from the Arabian name Ri'B al Ohill, the Demon's Head. This test contains an example of call-by-name. It is printed in Chapter 11 of the Hands-On Astrophysics manual. Galaxies | 2009 October: Unicode – The ⏨ (Decimal Exponent Symbol) for floating point notation was added to Unicode 5.2 for backward compatibility with historic Buran programme ALGOL software. The text below was written by Dr. John R. Percy, former AAVSO president, and Dr. Janet A. Mattei, AAVSO director. ALGOL 60 allowed for two evaluation strategies for parameter passing: the common call-by-value, and call-by-name. produced a new line on the teleprinter). One became aggravated when one's good ideas were discarded along with the bad ones of others. The Cepheids and RR Lyrae stars are typical examples of such variables. The two times of minimum light determined are HJD 2,445,263.0296 and HJD 2,445,739.0030. "...the Gorgon's head, a ghastly sight, deformed and dreadful, and a sight of woe". All ALGOL's characters are also part of the Unicode standard and most of them are available in several popular fonts. The text below was written by Dr. John R. Percy, former AAVSO president, and Dr. Janet A. Mattei, AAVSO director. The explosive (or eruptive) variables include novas, supernovas, and similar stars that undergo sudden outbursts of radiant energy, which results in rapid brightening. John Goodricke of England is credited with the discovery of Algol's periodicity in 1782-83. ALGOL heavily influenced many other languages and was the standard method for algorithm description used by the Association for Computing Machinery (ACM) in textbooks and academic sources until object-oriented languages came around, for more than thirty years. Special sequences were placed in double quotes (e.g. It is printed in Chapter 11 of the Hands-On Astrophysics manual. Its variability was cited in a 1783 paper by William Herschel as evidence of a planet in orbit about the star. An observation of the stellar system Algol showing a 3 hour X-ray flare It was originally published in the Royal Astronomical Society of It is printed in Chapter 11 of the Hands-On Astrophysics manual. IMAGES | Algol fades and rebrightens like clockwork every 2 days 20 hours 49 minutes. There were three major specifications, named after the years they were first published: ALGOL 68 is substantially different from ALGOL 60 and was not well received, so that in general "Algol" means ALGOL 60 and dialects thereof. system. More recently, the name Algol has been given to a violent video game. The changes in brightness may be periodic, semiregular, or completely irregular. ALGOL 60 did however become the standard for the publication of algorithms and had a profound effect on future language development. • May 8 – 00:13 UT It was revised and expanded by Peter Naur for ALGOL 60, and at Donald Knuth's suggestion renamed Backus–Naur form. The authors are John M. Blondin, Mercedes T. Richards & Michael L. Malinowski. Even astrologers refer to it as the worst star in the heavens to be involved with. This is because it can be observed with the unaided eye and it has a relatively short period of less than three days. The following code samples are ALGOL 68 versions of the above ALGOL 60 code samples. Be on the lookout for your Britannica newsletter to get trusted stories delivered right to your inbox. The different syntaxes permitted it to use different keyword names and conventions for decimal points (commas vs periods) for different languages. • May 30 – 22:45 UT. a scale height of 0.2 stellar radii anchored to the K subgiant in the In this capacity I was the editor of the ALGOL 60 report, produced as the result of the ALGOL 60 meeting in Paris in January 1960."[9]. In the language of the "Algol 68 Report" the input/output facilities were collectively called the "Transput". Now that every time swap is referenced, it is reevaluated. Let us know if you have suggestions to improve this article (requires login). John Goodricke was the EXOSAT light curve of Algol An observation of the stellar system Algol showing a 3 hour X-ray flare which had at its peak a luminosity of 10 31 ergs/sec and a temperature of 60 million degrees. The relative brightness of the system is plotted against time. [26][27][28], 1964: GOST – The 1964 Soviet standard GOST 10859 allowed the encoding of 4-bit, 5-bit, 6-bit and 7-bit characters in ALGOL.[29]. The light curve for Algol showing the primary eclipse and secondary eclipse, each of which occurs every 2.867 days. However, this remains unsupported by any other real evidence. A secondary eclipse takes place The International Algebraic Language (IAL), renamed ALGOL 58, was highly influential and generally considered the ancestor of most of the modern programming languages (the so-called Algol-like languages). J. • May 13 – 17:51 UT Light Curves and Phase A light curve is a plot showing the brightness variation of a source with time. • May 22 – 08:18 UT Reynolds's idealized Algol also made a convincing methodological argument regarding the suitability of local effects in the context of call-by-name languages, to be contrasted with the global effects used by call-by-value languages such as ML. The conceptual integrity of the language made it one of the main objects of semantic research, along with Programming Computable Functions (PCF) and ML. SAMELINE suppresses the carriage return + line feed normally printed between arguments. At first it was believed that a planet was causing the eclipses. Sounds rather more like members of a hard rock goth band than a beautiful astronomical object. For instance: ×, ÷, ≤, ≥, ≠, ¬, ∨, ∧, ⊂, ≡, ␣ and ⏨. Copyright © 2005 - 2015 Emil Neata - All Rights Reserved. Algol is an eclipsing binary star system 93 light-years away as determined by the Hipparcos satellite. Algol varies in V magnitude from 2.1 at maximum to 3.4 at primary minimum, with a period of 2.867315 days; this period, however, is slowly lengthening. A brief treatment of variable stars follows. In the sense that the syntax of most modern languages is "Algol-like",[3] it was arguably the most influential of the four high-level programming languages among which it was roughly contemporary: FORTRAN, Lisp, and COBOL. To ancient and medieval astrologers Algol was the most dangerous and unfortunate star in the heavens, which seems to suggest that its strange variability might have been noticed in antiquity. [4] It was designed to avoid some of the perceived problems with FORTRAN and eventually gave rise to many other programming languages, including PL/I, Simula, BCPL, B, Pascal, and C. ALGOL introduced code blocks and the begin...end pairs for delimiting them. The ICT 1900 series Algol I/O version allowed input from paper tape or punched card. Not. We also have Al Ghul meaning Mischief-maker. the flare shows that this event occurred in a magnetic loop structure with 1968: The "Algol 68 Report" – used extant ALGOL characters, and further adopted →, ↓, ↑, □, ⌊, ⌈, ⎩, ⎧, ○, ⊥, and ¢ characters which can be found on the IBM 2741 keyboard with typeball (or golf ball) print heads inserted (such as the APL golf ball).

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