The most common function is the route display. However, there are many different arrow symbols that are used in other contexts:
The use of symbolic arrows to indicate direction can be proven since the 18th century. The illustration of a pointing hand (manicle, Latin for "small hand") or even a foot is much older.
In mathematics arrows have different meanings:
- means: "(The consequence ) converges against (for )"
- means: " follows from "
- means: " is equivalent to " or "exactly if"
- defines a function with the property:
- denotes a function having a definition set and a target set ; Special forms such as or for injective or surjective functions are also common.
- An arrow above a symbol ( ) means that it is a vector .
They are also used in chemistry and physics to represent individual electrons (↑) and electron pairs (⇅ or ⇈) in molecular orbital diagrams or to represent the electron spin , as well as the nuclear spin .
Arrows have different meanings in road traffic: an arrow on a lane either indicates (or announces) a lane to turn, or indicates the imminent end of the lane and prompts the driver to change to another lane. On several traffic signs (eg: "Priority over oncoming traffic ", "Oncoming traffic has priority", "(Restricted) stopping prohibition beginning / further / end") arrows describe traffic flows or indicate the scope of the traffic sign. In addition, signs are often in the shape of an arrow to indicate their direction.
In enumerations of the arrow is often called Bullet ( enumeration symbol used) instead of an indent.
Schematic drawings and plans
The index finger ☞ was a substitute for an arrow in texts until the 20th century.
In a lexicon entry , an arrow in front of another word refers to an article with the same name. Depending on the typography of the lexicon, the arrow symbol points to the right (→) or up (↑).
The arrow can either serve as a forwarding in the sense of "see below" ( Zuckergast → Silberfischchen ) or a reference to a further article ( Willberg, Hans Peter (* October 4, 1930 in Nuremberg, † May 29, 2003) was a German → Typographer ).
The arrow is mainly used in printed dictionaries because it can be replaced by a hyperlink in digital reference works .
In the computer character code Unicode there is a separate code block for arrow symbols, the Unicode block arrows ( Arrows ), the area code to 2190 16 to 21FF 16 is, and incorporates many of the symbols described above.
In the diagnostic scheme in dentistry , tilted or elongated (seemingly elongated) teeth are characterized with arrows that indicate the direction of the tilt, elongation or tooth migration : → or ←, ↑ or ↓. A gap closure after a tooth loss is indicated by two opposite brackets) (. If the gap has been closed by tooth migration, additional arrows are indicated before and after the brackets: →) (←.
- Robert J. Finkel: History of the Arrow . 2015
- Quantities, Units and Symbols in Physical Chemistry (“Green Book”; PDF; 2.0 MB), IUPAC .
- Rudolf W. Ott: Clinic and Practice Guide Dentistry . Georg Thieme Verlag, 2003, ISBN 978-3-13-131781-0 , p. 448.