Editing Interpunct (section)

==In mathematics and science==
{{Infobox symbol
| mark     = ⋅<!--U+22C5-->
| name     = Multiplication dot
| unicode  = {{unichar|22C5|Dot operator|html=}}
| see also = {{unichar|2219|nlink=Bullet operator |html=}}
}}

Up to the mid twentieth century, and sporadically even much later, the interpunct could be found used as the [[decimal marker|decimal point]] in British publications, such as tables of constants (e.g., "{{math|1=π = 3·14159}}").  Conversely the multiplication sign was a full stop (period).{{Citation needed|date=July 2021}}

In publications conforming to the standards of the [[International System of Units]], as well as the multiplication sign (×), the centered dot (dot operator) or space (often typographically a [[non-breaking space]]) can be used as a multiplication sign.{{Citation needed|date=October 2024}}  Only a [[comma]] or [[full stop|full stop (period)]] may be used as a decimal marker.{{Citation needed|date=October 2024}} The centered dot can be used when multiplying units, as in {{math|m·kg·s<sup>−2</sup>}} for the [[newton (unit)|newton]] expressed in terms of SI base units.{{Citation needed|date=October 2024}}  In the United States, the use of a centered dot for the multiplication of numbers or values of quantities is discouraged by [[NIST]].<ref>{{cite web |url=https://physics.nist.gov/cuu/pdf/sp811.pdf#10.5.2 |title=Guide for the Use of the International System of Units (SI) |page=37 |first1=Ambler |last1=Thompson |first2=Barry N. |last2=Taylor |date=March 2008 |publisher=[[National Institute of Standards and Technology]] |access-date=24 June 2021}}</ref>

In [[mathematics]], a small middle dot can be used to represent [[multiplication]]; for example, <math>x\cdot y</math> for multiplying <math>x</math> by <math display="inline">y</math>. When dealing with [[scalar (mathematics)|scalars]], it is interchangeable with the [[multiplication sign]] ({{char|×}}), as long as the multiplication sign is between numerals such that it would not be mistaken as variable <math display="inline">x</math>. For instance, <math display="inline">2\cdot3y</math> means the same thing as <math display="inline">2\times3y</math>. However, when dealing with [[vector (geometry)|vectors]], the dot operator denotes a [[dot product]] (e.g. <math display="inline">\vec{x}\cdot\vec{y}</math>, a scalar), which is distinct from the [[cross product]] (e.g. <math>\vec{x}\times\vec{y}</math>, a vector).

Another usage of this symbol in mathematics is with [[function (mathematics)|functions]], where the dot is used as a placeholder for a [[Argument of a function|function argument]], in order to distinguish between the (general form of the) function itself and the value or a specific form of a function evaluated at a given point or with given specifications.<ref>{{Cite web | url=https://en.wiktionary.org/wiki/%C2%B7#Symbol |title = · - Wiktionary}}</ref><ref>{{cite book |last1=Adams |first1=Michael D. |title=Signals and Systems |date=2020 |isbn=978-1-55058-674-9 |page=12 |edition=3.0 |url=https://ece.engr.uvic.ca/~frodo/sigsysbook/downloads/signals_and_systems-3.0.pdf |access-date=22 July 2021}}</ref> For example, <math display="inline">f(\cdot)</math> denotes the function <math display="inline">x\mapsto f(x)</math>, and <math>\theta(s,a,\cdot)</math> denotes a [[partial application]], where the first two arguments are given and the third argument shall take any valid value on its domain.

The [[Bullet (typography)#Other forms of use|bullet operator]], {{char|∙}}, U+2219, is sometimes used to denote the [[logical conjunction|"AND" relationship]] in formal [[logic]].

In [[computing]], the middle dot is usually displayed (but not printed) to indicate [[Whitespace character|white space]] in various software applications such as [[word processing]], [[graphic design]], web layout, [[desktop publishing]] or [[software development]] programs. In some [[word processor]]s, interpuncts are used to denote not only [[hard space]] or space characters, but also sometimes used to indicate a space when put in paragraph format to show indentations and spaces. This allows the user to see where white space is located in the document and what sizes of white space are used, since normally white space is invisible so tabs, spaces, non-breaking spaces and such are indistinguishable from one another.

In [[chemistry]], the middle dot is used to separate the parts of formulas of [[addition compound]]s, mixture salts or solvates (typically hydrates), such as of [[copper(II) sulfate|copper(II) sulphate pentahydrate]], {{math|CuSO<sub>4</sub>·5H<sub>2</sub>O}}. The middle dot should not be surrounded by spaces when indicating a chemical adduct.<ref>{{cite book |last1=Connelly|first1=Neil G.|last2=Damhus|first2=Ture|last3=Hartshorn|first3=Richard M.|last4=Hutton|first4=Alan T. |title=Nomenclature of Inorganic Chemistry, IUPAC Recommendations 2005 (the "Red Book") |date=2005 |isbn= 0-85404-438-8 |page=56 |url=https://iupac.org/wp-content/uploads/2016/07/Red_Book_2005.pdf |access-date=10 January 2023}}</ref>