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Algol 1. The common name of the star beta Persei. This star has the unusual property of having regular variations in brightness: its magnitude changes regualrly between 2.3 and 3.5 over a period of 2 days, 20 hours and 49 minutes. Algol is what is known as an [eclipsing binary variable]?: it is actually two stars in close orbit about one another, and when (as seen from Earth's line of sight), the second, dimmer star passes in front of its companion once per orbit, the amount of light reaching earth is decreased, followed by an increase as the companion moves out of the way. 2. A computer programming language originally developed in 1958, which was named for the algorithmic process of definition of a programming problem. Short for Algorithmic Language. In some ways, it was a reaction to Fortran and was a precursor to Pascal. It uses words to bracket blocks and was the first to use begin end pairs. There were three main official versions of Algol: [Algol 58]?, [Algol 60]?, and [Algol 68]?. Of these, [Algol 60]? was by far the most influential. ([Algol 60]? produced [Algol W]?, which in turn produced Pascal.) Each of the official Algol versions is named after the year in which it was published. Algol was developed jointly by a committee of European and American computer scientists. It had at least three different syntaxes: a reference syntax, a publication syntax, and an implementation syntax. The different syntaxes permitted it to use different keyword names, conventions for decimal points (commas vs. periods) for different languages. [John Backus]? developed the [Backus Normal Form]? method of describing programming languages specifically for [Algol 58]?. It was revised and expanded by [Peter Naur]? to the [Backus Naur Form]? for [Algol 68]?. --- for more info about Algol 68, see also http://vestein.arb-phys.uni-dortmund.de/~wb/RR/rrTOC.html |
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Algol is the common name of the star Beta Persei. This star has the unusual property of having regular variations in brightness: its magnitude changes regularly between 2.3 and 3.5 over a period of 2 days, 20 hours and 49 minutes. Algol is what is known as an [eclipsing binary]?: it is actually two stars in close orbit about one another, and when (as seen from Earth's line of sight), the second, dimmer star passes in front of its companion once per orbit, the amount of light reaching earth is decreased, followed by an increase as the companion moves out of the way. Algol is also a computer programming language; see Algol programming language. |
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