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Letters and Letter-like Forms

Greek Letters

The complete collection of Greek letters in Mathematica.

You can use Greek letters as the names of symbols. The only Greek letter with a built-in meaning in StandardForm is Pi, which Mathematica takes to stand for the symbol Pi.
Note that even though Pi on its own is assigned a built-in meaning, combinations such as Pi2 or xPi have no built-in meanings.
The Greek letters CapitalSigma and CapitalPi look very much like the operators for sum and product. But as discussed above, these operators are different characters, entered as \[Sum] and \[Product] respectively.
Similarly, Epsilon is different from the Element operator \[Element], and Mu is different from µ or \[Micro].
Some capital Greek letters such as \[CapitalAlpha] look essentially the same as capital English letters. Mathematica however treats them as different characters, and in TraditionalForm it uses \[CapitalBeta], for example, to denote the built-in function Beta.
Following common convention, lower-case Greek letters are rendered slightly slanted in the standard fonts provided with Mathematica, while capital Greek letters are unslanted. On Greek systems, however, Mathematica will render all Greek letters unslanted so that standard Greek fonts can be used.
Almost all Greek letters that do not look similar to English letters are widely used in science and mathematics. The capital xi CapitalXi is rare, though it is used to denote the cascade hyperon particles, the grand canonical partition function and regular language complexity. The capital upsilon CapitalUpsilon is also rare, though it is used to denote particles, as well as the vernal equinox.
Curly Greek letters are often assumed to have different meanings from their ordinary counterparts. Indeed, in pure mathematics a single formula can sometimes contain both curly and ordinary forms of a particular letter. The curly pi CurlyPi is rare, except in astronomy.
The final sigma FinalSigma is used for sigmas that appear at the ends of words in written Greek; it is not commonly used in technical notation.
The digamma Digamma, koppa Koppa, stigma Stigma and sampi Sampi are archaic Greek letters. These letters provide a convenient extension to the usual set of Greek letters. They are sometimes needed in making correspondences with English letters. The digamma corresponds to an English w, and koppa to an English q. Digamma is occasionally used to denote the digamma function PolyGamma[x].

Variants of English Letters

Some commonly used variants of English letters.

By using menu items in the notebook front end, you can make changes in the font and style of ordinary text. However, such changes are usually discarded whenever you send input to the Mathematica kernel.
Script, gothic and double-struck characters are, however, treated as fundamentally different from their ordinary forms. This means that even though a C that is italic or a different size will be considered equivalent to an ordinary C when fed to the kernel, a double-struck DoubleStruckCapitalC will not.
Different styles and sizes of C are treated as the same by the kernel. But gothic and double-struck characters are treated as different.
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In standard mathematical notation, capital script and gothic letters are sometimes used interchangeably. The double-struck letters, sometimes called blackboard or openface letters, are conventionally used to denote specific sets. Thus, for example, DoubleStruckCapitalC conventionally denotes the set of complex numbers, and DoubleStruckCapitalZ the set of integers.
Dotless i and j are not usually taken to be different in meaning from ordinary i and j; they are simply used when overscripts are being placed on the ordinary characters.
\[WeierstrassP] is a notation specifically used for the Weierstrass P function WeierstrassP.
full namesaliases
\[ScriptA] - \[ScriptZ]EscapeKeyscaEscapeKey - EscapeKeysczEscapeKeylowercase script letters
EscapeKeyscAEscapeKey - EscapeKeyscZEscapeKeyuppercase script letters
\[GothicA] - \[GothicZ]EscapeKeygoaEscapeKey - EscapeKeygozEscapeKeylowercase gothic letters
EscapeKeygoAEscapeKey - EscapeKeygoZEscapeKeyuppercase gothic letters
EscapeKeydsaEscapeKey - EscapeKeydszEscapeKeylowercase double-struck letters
EscapeKeydsAEscapeKey - EscapeKeydsZEscapeKeyuppercase double-struck letters
EscapeKey$aEscapeKey - EscapeKey$zEscapeKeylowercase formal letters
EscapeKey$AEscapeKey - EscapeKey$ZEscapeKeyuppercase formal letters

Complete alphabets of variant English letters.

Formal Symbols

Symbols represented by formal letters, or formal symbols, appear in the output of certain functions. They are indicated by gray dots above and below the English letter.
DifferentialRoot automatically chooses the names for the function arguments.
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Formal symbols are Protected, so they cannot be accidentally assigned a value.
Trying to modify a formal symbol fails.
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This means that expressions depending on formal symbols will not be accidentally modified.
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Specific values for formal symbols can be substituted using replacement rules.
Verify that the defining equations hold for cosine.
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Formal symbols can be temporarily modified inside of a Block because Block clears all definitions associated with a symbol, including Attributes. Table works essentially like Block, thus also allowing temporary changes.
Assign a temporary value to FormalY:
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In most situations modifying formal symbols is not necessary. Since in DifferentialRoot formal symbols are used as names for the formal parameters of a function, the function should simply be evaluated for the actual values of arguments.
Evaluating the function substitutes x for FormalX and y for FormalY.
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It is possible to define custom typesetting rules for formal symbols.
Use coloring to highlight formal symbols.
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The formatting rules were attached to MakeBoxes. Restore the original formatting:
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Hebrew Letters

Hebrew characters.

Hebrew characters are used in mathematics in the theory of transfinite sets; Aleph0 is for example used to denote the total number of integers.

Units and Letter-Like Mathematical Symbols

Units and letter-like mathematical symbols.

Mathematica treats ° or \[Degree] as the symbol Degree, so that, for example, 30° is equivalent to 30Degree.
Note that µ, Angstrom and EmptySet are all distinct from the ordinary letters Mu (\[Mu]), RightTriangle (\[CapitalARing]) and Ø (\[CapitalOSlash]).
Mathematica interprets Infinity as Infinity, ExponentialE as E, and both ImaginaryI and ImaginaryJ as I. The characters ExponentialE, ImaginaryI and ImaginaryJ are provided as alternatives to the usual uppercase letters E and I.
DoubledPi and DoubledGamma are not by default assigned meanings in StandardForm. You can therefore use DoubledPi to represent a pi that will not automatically be treated as Pi. In TraditionalForm DoubledGamma is interpreted as EulerGamma.

Operators that look like letters.

Del is an operator while HBar, ° and ¥ are ordinary symbols.
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Shapes, Icons and Geometrical Constructs

Shapes.

Shapes are most often used as "dingbats" to emphasize pieces of text. But Mathematica treats them as letter-like forms, and also allows them to appear in the names of symbols.
In addition to shapes such as \[EmptySquare], there are characters such as \[Square] which are treated by Mathematica as operators rather than letter-like forms.

Icons.

You can use icon characters just like any other letter-like forms.
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Notation for geometrical constructs.

Since Mathematica treats characters like Angle as letter-like forms, constructs like AngleBC are treated in Mathematica as single symbols.

Textual Elements

Characters used for punctuation and annotation.

Other characters used in text.

Characters used in building sequences and arrays.

The under and over braces grow to enclose the whole expression.
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Extended Latin Letters

Mathematica supports all the characters commonly used in Western European languages based on Latin scripts.

Variants of English letters.

Most of the characters shown are formed by adding diacritical marks to ordinary English letters. Exceptions include \[SZ] ß, used in German, and \[Thorn] Thorn and \[Eth] Eth, used primarily in Old English.
You can make additional characters by explicitly adding diacritical marks yourself.
char Ctrl+& mark Ctrl+Spaceadd a mark above a character
char Ctrl++ mark Ctrl+Spaceadd a mark below a character

Adding marks above and below characters.

formaliasfull name
'(keyboard character)\[RawQuote]acute accent
PrimeEscapeKey'EscapeKey\[Prime]acute accent
`(keyboard character)\[RawBackquote]grave accent
ReversePrimeEscapeKey`EscapeKey\[ReversePrime]grave accent
. .(keyboard characters)umlaut or diaeresis
^(keyboard character)\[RawWedge]circumflex or hat
EmptySmallCircleEscapeKeyesciEscapeKey\[EmptySmallCircle]ring
.(keyboard character)\[RawDot]dot
~(keyboard character)\[RawTilde]tilde
_(keyboard character)\[RawUnderscore]bar or macron
HacekEscapeKeyhcEscapeKey\[Hacek]hacek or check
BreveEscapeKeybvEscapeKey\[Breve]breve
DownBreveEscapeKeydbvEscapeKey\[DownBreve]tie accent
DoublePrimeEscapeKey''EscapeKey\[DoublePrime]long umlaut
CedillaEscapeKeycdEscapeKey\[Cedilla]cedilla

Diacritical marks to add to characters.