Obelus

The Divided character is a mathematical operator for the division.

Symbols for the Division

As Divided characters a colon (:), a colon followed by a mid- line ( ÷ ) or a slash ( / ) are used in the text block. Fractures are represented by a fraction bar, similar to the slash in the text block. In the formula set numerator and denominator of a fraction are shown one above the other, with the now horizontal fraction line as a dividing line.

In most countries, as in Germany, in the school mathematics preferably, the colon ( :) used; in the English language and on the calculators Obelus sign ( ÷ ) is mostly used. In the higher mathematics are found almost exclusively the fraction notation (, rarely ) or the spelling as multiplication by the reciprocal of (). The slash (/) is found mainly in programming languages.

History of Symbols

The oldest symbol appears to be the slash (/). It was first used by the English mathematician William Oughtred in his work Clavis Mathematicae, published in 1631 in London.

The German scientist Gottfried Wilhelm Leibniz used the colon (:). Leibniz used the Division colon for the first time in 1684 in Acta eruditorum. Before Leibniz Englishman Johnson already had the symbol published in 1633 in a book, but only as a break character and not for the division in the strict sense.

Johann Rahn introduced the composite of colon and underscore characters ( ÷ ) for the division. Together with the symbol for multiplication (*), this appears for the first time in his book Teutsche Algebra, published 1659th Rahn Divided character is sometimes referred to as English Divided sign because it is more widely used in the English -speaking world. Its origins, however, in Germany.

Representation in computer systems

Coding

The international character encoding standard Unicode contains several Shared characters and signs for closely related applications. You are in the following positions:

In the ASCII character set of the colon is only included, which is why many older computer systems could only represent him. Already the ASCII extensions to ISO 6937 in 1983 and ISO 8859-1 ( Latin 1) of 1986 contained the Divided sign ( ÷ ). The representation of the Divided sign ( ÷ ) on modern computers, can be problematic, as the common ISO -8859 encodings with the newer Unicode encodings such as UTF -8 do not match.

Replacement by other characters

Because of the lack of Divided characters on the keyboard, the characters often through the simple colon ( :) or a single slash (/) to be replaced.