Tilde

The tilde (~) is a grapheme with several uses. The name of the character comes from Spanish, from the Latin titulus meaning a title or superscription, and is pronounced ['tɪl.də], in English, or ['til.ðe], in Spanish. It was originally written over a letter as a mark of abbreviation (see below), but has since acquired a number of other uses as a diacritic mark or a character in its own right. In the latter capacity (especially in lexicography) it is also sometimes known as the swung dash (usually lengthened to ⁓).

Diacritical use

In languages, the tilde is a diacritic mark (~) placed over a letter to indicate a change in pronunciation, such as nasalisation. It was originally used to make abbreviations in Latin documents. When an n or m followed a vowel, it was often omitted, and a tilde (i.e. a small n) was placed over the preceding vowel to indicate the loss of the nasal. This is the origin of the use of tilde to indicate nasalization. The practice of using the tilde over a vowel to indicate omission of an "n" or "m" continued in printed books in French as a means of reducing text length until the 17th century. The tilde was also used occasionally over other letters to indicate other abbreviations, such as over the letter "q" to signify the word "que" (fr. "that").

In Estonian, õ is a separate letter, representing a separate vowel sound.

In the polytonic orthography of Greek, the tilde appears as a variant of the circumflex accent, representing a rise in pitch followed by a return to standard pitch.

In Portuguese, the tilde marks a nasal vowel.

In Spanish and Galician, tilde over n (ñ) is a separate letter (called eñe) and is a palatal n (IPA [ɲ]). This phoneme is written nh in Portuguese, gn in French and Italian, ny in Catalan, Hungarian and Swahili, ň in Czech, nj in Serbo-Croatian, and ń in Polish. The sound is that of the "gn" in "lasagna" and the "ni" sound in "onion" and "union" in many dialects of English. The Spanish word tilde refers to any accent mark placed over a vowel. For example, the acute accent in the word Olé is also called a tilde.

In Vietnamese, a tilde over a vowel represents a dipping (ngã) tone.

In the International Phonetic Alphabet (IPA), the tilde is used over a symbol to mark nasalization and through a symbol to mark velarization. That is, [ljõ] is the French city Lyon, and [kʊ:ɫ] is the Australian English pronunciation of "cool", with the "dark l".

Logic

In logic, it represents the negation of a proposition: thus ~p means "not p".

Electronics

It can approximate the sine wave symbol (∿, U+223F), which is used in electronics to indicate alternating current, in place of +, −, or ⎓ for direct current.

Punctuation

It is sometimes used as punctuation (instead of a hyphen or dash) between two numbers, to indicate that they are a range, rather than subtraction, or a hyphenated number (such as a part number or model number). Japanese and other Asian languages almost always use this convention, but it is often done for clarity in other languages as well. For example: 12~15 means "12 to 15", ~3 means "up to three" and 100~ means "100 and greater". In Japanese, the tilde is also used to separate a title and a subtitle in the same line.

Mathematics

In mathematics, the tilde, often pronounced "twiddle," is often used to denote an equivalence relation between two objects. Thus x ~ y means x "is equivalent to" y (Note that this is quite different from stating that x equals y). Especially, it can be used to denote the asymptotical equality of two functions. For example, f(x) ~ g(x), means that lim_x→∞ f(x)/g(x) = 1.

In English it is often used to represent approximation, for example ~10 would mean "approximately 10". Similar symbols are used in mathematics, such as in π ≈ 3.14, "π is about equal to 3.14". Since the double-tilde (≈) is not available from the keyboard except on the Macintosh (where it is Option-x), the tilde (~) became a substitute for use in typed entry. There is also a triple-tilde (≋), which is used to show congruence.

In mathematical logic, ~ is used to represent negation. ~p means "not p". See the logic section above.

In statistics and probability theory, ~ means "is distributed as". See random variable.

Computing

Directories and URLs

In Unix shells, the tilde indicates the current user's home directory (e.g., /home/username). When prepended to a particular username, it indicates that user's home directory (e.g., ~janedoe for the home directory of user janedoe, typically /home/janedoe). When some Unix shell commands overwrite a file, they can be made to keep a backup by renaming the original file as filename~.

Used in URLs on the World Wide Web, it often denotes a personal website on a Unix-based server. For example, http://www.widgets.com/~johndoe/ might be the personal web site of John Doe. This mimics the Unix shell usage of the tilde. However, when accessed from the web, file access is usually directed to a subdirectory in the user's home directory, such as /home/username/public_html or /home/username/www.

In URLs, the characters %7E (or %7e) may substitute a tilde if an input device lacks a tilde key. Thus, http://www.widgets.com/~johndoe/ and http://www.widgets.com/%7Ejohndoe/ are essentially the same URL.

Computer languages

It is used in the Perl programming language as part of the pattern match operators for regular expressions:

• $a =~ /regex/ returns true if the variable is matched.
• $a !~ /regex/ returns false if the variable is matched.

The popularity of Perl's regular expression and syntax has led to the use of these operators in other programming languages, such as Ruby.

In the C and C++ programming languages, the tilde character is used to invert the bits of an integer. In C++, the tilde is also used as the first character in a class's method name (where the rest of the name must be the same name as the class) to indicate a destructor - a special method which is called at the end of the object's life.

In the D programming language, the tilde is used as an array concatenation operator, as well as to indicate an object destructor.

In the CSS stylesheet language, the tilde is used for the indirect adjacent combinator as part of a selector.

In the Inform programming language, the tilde is used to indicate a quotation mark inside a quoted string.

In "text mode" of the LaTeX typesetting language a stand-alone tilde can be obtained with \~{} and for use as a diacritics, e.g., like \~{n} rendering "ñ". In "math mode" a stand-alone tilde can be written as \tilde{~} and as diacritics, e.g., \tilde{x}. For a wider tilde the \widetilde can be used. The \sim command produce a tilde-like character that is often used in probability mathematical equations, and the double-tilde is obtained with \approx. In both text and math mode a tilde on its own (~) is rendering a white space with no line breaking.

The Emacs text editor forms the names used for backup files by appending a tilde to the original file name.

Microsoft filenames

The tilde was part of Microsoft's name mangling scheme when it developed the VFAT filesystem. This upgrade introduced long filenames to Microsoft Windows, and permitted additional characters (such as the space) to be part of filenames, which were prohibited in previous versions. Programs written prior to this development could only access filenames in the so-called 8.3 format—the filenames consisted of a maximum of eight alphanumeric characters, followed by a period, followed by three more alphanumeric characters. In order to permit these legacy programs to access files in the VFAT filesystem, each file had to be given two names—one long, more descriptive one, and one that conformed to the 8.3 format. This was accomplished with a name-mangling scheme in which the first six characters of the filename are followed by a tilde and a digit. For example, "Program Files" becomes "PROGRA~1".

Other uses

Computer programmers use the tilde in various ways and often call the symbol (as opposed to the diacritic) a squiggle or a twiddle. According to the Jargon File, other synonyms sometimes used in programming include not, approx, wiggle, enyay and (humourously) sqiggle.

See History of the tilde for a history of how the tilde came to become part of the standard computer character sets.

In Google search, the tilde entered before a search query word displays listings with that word and synonyms of it. [1]

To type a tilde on a Spanish keyboard, you can use AltGr+4. On the Macintosh keyboard, Option-n followed by another letter places the tilde over that letter.

On most Windows diagnostic programs a tilde is put infront of the processor speed as a way of saying approximately, as in e.g. Processor Speed : ~2795MHz.

In IRC, a tilde is a rank of administration symbol for the founder of a channel.

In MediaWikis, four tildes is a placeholder for information about someone who left an edit, which is automatically filled in by MediaWiki.

Lexicography

In dictionaries, both bilingual and monolingual, tilde is usually referred to as swung dash. It is often used to replace the headword of an entry when it occurs within the entry, in order to save space. For example, ~ing would represent singing at the entry for sing.

Juggling notation

In the juggling notation system beatmap, tilde can be added to either "hand" in a pair of fields to say "cross the arms with this hand on top". Mills Mess is thus represented as (~2x,1)(1,2x)(2x,~1)* [2].

Colloquial usage

Tilde has a rare colloquial usage in the United Kingdom where it can be used to denote sleazy, sordid, or otherwise base behaviour in written form. An example of this would be, "I gave her some real ~~~ and she put out on the spot."

Tilde is also an often used symbol in order to stress an argument. "I rule!~~" This probably came from accidental transposition of the tilde and the exclamation point (!) which resides next to it on US keyboards.

In electronic communication (email, text, sms) the tilde can be taken to mean approximately. Example "~50%" can be used to express "approximately 50 percent".

In many instances (some Asian image boards and lately the anime fandom) the tilde is used to make a word or phrase look cute, more feminine or pleasant. "Hello~~" Some theorize that it came from the above "typo" etymology, but another theory is that it derives from a similar looking character used in Japanese to lengthen vowels.

The tilde is also used in some comic books or other writings to extend the sound of the last syllable of a word. Example the phrase "Brian NO!~" would be pronounced "Brian NOOOOOOOOOOO!".

Proper names

• In Denmark, Norway and Sweden, Tilde is a personal name.
• In Latvia, Tilde is a major IT company (http://www.tilde.lv/).

Popular culture

• On the TV Network Tech TV, there are certain shows with two virtual characters, "Tilde" and "Dash".
• On certain Counter-Strike Internet Forums, the slogan "Keep away from that tilde" is used, referring to that in most First Person Shooter games, by default the tilde key on the keyboard opens up the console, which allows cheating.

See also

• Ã
• Õ
• Ñ
• Diacritic
• Special characters
• Punctuation

External links

• History of the Tilde
• Diacritics Project All you need to design a font with correct accents