Obelus
From Wikipedia, the free encyclopedia
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- The word "obelus" is also an alternative name for the dagger (†) symbol.
An obelus (pl. "obeli") is a symbol consisting of a line with dots above and below, 
, used to represent the mathematical division operation. This symbol is also known as a division sign. The word "obelus" comes from the Greek word for a sharpened stick, spit, or pointed pillar. This is the same root as that of the word "obelisk". Originally this sign (or a plain line) was used in ancient manuscripts to mark passages which were suspected of being corrupted or spurious.
The obelus, invented by Aristarchus to mark suspected passages in Homer, is frequent in MSS. [i.e. manuscripts] of the Gospel to mark just those sections, like the Pericope in John, which modern editors reject. The first corrector of א, probably the contemporary διορθωτής, was at pains to enclose in brackets and mark with dots for deletion two famous passages in Luke written by the original scribe which, being absent from B W 579 and the Egyptian versions, we infer were not accepted in the text at that time dominant in Alexandria, viz. the incident of the "Bloody Sweat" in Gethsemane (Lk.xxi.43 f.) and the saying "Father forgive them" (Lk.xi.34). [1]
The obelus was first used as a symbol for division in 1659 in the algebra book Teutsche Algebra by Johann Rahn. Some think that John Pell, who edited the book, may have been responsible for this use of the symbol. The obelus had been used by some writers to represent subtraction, and that usage continued in some parts of Europe (including Norway and, until fairly recently, Denmark). The symbol had also been used occasionally in Polish language typography to represent ranges (such as 6–9), although this usage is mostly discontinued.
Today the obelus remains in occasional use, primarily as a standalone symbol for the division operation itself (as on a calculator), or as an operator in elementary arithmetic. In most contexts division is now signified in other ways, usually by writing the operands one above the other separated by a line, or on the same line with the slash (or solidus) as the symbol signifying division. In many non-Anglophone countries the colon is used as a division sign: “a divided by b” is written as a : b.
In the Unicode character set, the obelus is known as a "division sign" and has the code point U+00F7. In HTML, it can be encoded as ÷ (at HTML level 3.2) or ÷ or ÷. To enter an obelus on a Windows computer, hold down the Alt key as you type 0247 on the number pad. On a Macintosh, hold down the Option key as you type the slash (/) character.
[edit] Notes
- ^ Burnett Hillman Streeter, The Four Gospels, London, Macmillan, 1924 [1] The Aristarchus referred to was presumably Aristarchus of Samothrace.
