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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 , in English, or , in Spanish. It was originally written over a letter as a mark of Abbreviation , 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 ), '''twiddle''' or the '''squiggle'''. DIACRITICAL USE In languages, the tilde is a Diacritic al mark (~) placed over a Letter to indicate a change in pronunciation, such as Nasalization . It was first used in the Polytonic Orthography of Ancient Greek , as a variant of the Circumflex Accent , representing a rise in Pitch followed by a return to standard pitch. Later, it was used to make Abbreviation s in medieval 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 missing letter. 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. It was also used in Spanish . The tilde was also used occasionally to make other abbreviations, such as over the letter "q" to signify the word ''que'' (Fr. "that"). Languages where the tilde is part of the symbol " ñ ", for the Palatal Nasal consonant include:
Languages and alphabets where the tilde is used as a sign of Nasalization include:
Languages and alphabets that use the tilde for other purposes:
LEXICOGRAPHY In Dictionaries , both bilingual and monolingual, the tilde is often referred to as a 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, ''~ enough'' would represent ''ironically enough'' at the entry for ''ironically''. LOGIC In written mathematical Logic , it represents Negation (e.g. "~''p''" equals "not ''p''".) Modern use has been replacing the tilde with the exclamation mark (!) for this purpose, to avoid confusion with Equivalence Relation s. 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 motto of the Catholic Monarchs , "tanto monta" ("it rises as much"), is written in this inscription as "tãto mõta"]] It is sometimes used as Punctuation (instead of a Hyphen or Dash ) between two Number s, 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 East 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." However in English, a tilde preceding a number sometimes represents an approximation (see the following section). In Japanese, the tilde is also used to separate a title and a subtitle in the same line. A Colon is usually used in English for this purpose. When used in conversations via email or instant messenger it might have been intended as a Sarcasm Mark or, in Asian cultures, as an extension of the final syllable to produce the same effect as "whyyyyyy" with "why~~". Used at the end of a word or sentence in fanfiction, it often denotes something said in a sing-song voice, or similar to the use in instant messengers and email, depending on context. MATHEMATICS In Mathematics , the tilde, sometimes 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 usually quite different from stating that ''x'' Equals ''y''.) The expression "''x'' ~ ''y''" is sometimes read aloud as "''x'' twiddles ''y''," perhaps as an analogue to the verbal expression of "''x'' = ''y''." There are two common contexts in which "~" is used to denote particular equivalence relations: It can be used to denote the Asymptotical Equality of two functions. For example, ''f''(''x'') ~ ''g''(''x''), means that limx→∞ ''f''(''x'')/''g''(''x'') = 1. Additionally, in Statistics and Probability Theory , ~ means "is distributed as." See Random Variable . There is also a triple-tilde ( ≋ ), which is often used to show Congruence , an equivalence relation in geometry. In English it is sometimes 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 on English Layouts ), the tilde (~) became a substitute for use in Typed entry. A tilde is also used to indicate "approximately equal to" (e.g. 1.902 ~= 2). This usage probably developed as a typed alternative to the libra symbol used for the same purpose in written mathematics, which is an equal sign (=) with the upper bar replaced by a bar with an upward hump or loop in the middle or, sometimes, a tilde. see Approximation . The symbol "≈" is also used for this purpose. A tilde placed below a letter in mathematics can represent a vector quantity. COMPUTING Directories and URLs In Unix Shell s, 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 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, Computer languages It is used in the Perl Programming Language as part of the pattern match operators for Regular Expression s:
The popularity of Perl's regular expression and syntax has led to the use of these operators in other programming languages, such as Ruby or the SQL variant of the database PostgreSQL . In the C and C++ programming languages, the tilde character is used as an Operator to invert all Bit s of an Integer (bitwise NOT), following the notation in logic (an ! causes a logical NOT, instead). 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 Max/MSP , a tilde is used to denote objects that process at the computer's sampling rate, i.e. mainly those that deal with sound. 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 ilde{~} and as diacritics, e.g., ilde{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 ( ~ |
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