# Letters and Letter‐like Forms

## Greek Letters

The complete collection of Greek letters in the Wolfram Language.

You can use Greek letters as the names of symbols. The only Greek letter with a builtin meaning in StandardForm is , which the Wolfram Language takes to stand for the symbol Pi.

Note that even though on its own is assigned a builtin meaning, combinations such as or have no builtin meanings.

The Greek letters and 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, is different from the operator [Element], and is different from or [Micro].

Some capital Greek letters such as [CapitalAlpha] look essentially the same as capital English letters. The Wolfram Language, however, treats them as different characters, and in TraditionalForm it uses [CapitalBeta], for example, to denote the builtin function Beta.

Following common convention, lowercase Greek letters are rendered slightly slanted in the standard fonts provided with the Wolfram System, while capital Greek letters are unslanted. On Greek systems, however, the Wolfram System 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 is rare, though it is used to denote the cascade hyperon particles, the grand canonical partition function, and regular language complexity. The capital upsilon 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 is rare, except in astronomy.

The final sigma is used for sigmas that appear at the ends of words in written Greek; it is not commonly used in technical notation.

The digamma , koppa , stigma , and 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 Wolfram Language kernel.

Script, gothic, and doublestruck 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 doublestruck will not.

Different styles and sizes of C are treated as the same by the kernel. But gothic and doublestruck characters are treated as different.
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In standard mathematical notation, capital script and gothic letters are sometimes used interchangeably. The doublestruck letters, sometimes called blackboard or openface letters, are conventionally used to denote specific sets. Thus, for example, conventionally denotes the set of complex numbers, and 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 names aliases EscscaEsc – EscsczEsc lowercase script letters EscscAEsc – EscscZEsc uppercase script letters EscgoaEsc – EscgozEsc lowercase gothic letters EscgoAEsc – EscgoZEsc uppercase gothic letters EscdsaEsc – EscdszEsc lowercase double‐struck letters EscdsAEsc – EscdsZEsc uppercase double‐struck letters Esc\$aEsc – Esc\$zEsc lowercase formal letters Esc\$AEsc – Esc\$ZEsc uppercase 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 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 y.
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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 x and y for y.
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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; is for example used to denote the total number of integers.

## Units and Letter‐like Mathematical Symbols

Units and letterlike mathematical symbols.

The Wolfram Language treats or \[Degree] as the symbol Degree, so that, for example, 30° is equivalent to 30Degree.

Note that , , and are all distinct from the ordinary letters (), (\[CapitalARing]), and (\[CapitalOSlash]).

The Wolfram Language interprets as Infinity, as E, and both and as I. The characters , , and are provided as alternatives to the usual uppercase letters E and I.

and are not by default assigned meanings in StandardForm. You can therefore use to represent a pi that will not automatically be treated as Pi. In TraditionalForm, is interpreted as EulerGamma.

Operators that look like letters.

is an operator while , , 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 the Wolfram Language treats them as letterlike 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 the Wolfram Language as operators rather than letterlike forms.

Icons.

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

Since the Wolfram Language treats characters like as letterlike forms, constructs like are treated in the Wolfram Language 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

The Wolfram Language 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] , used in German, and \[Thorn] and \[Eth] , used primarily in Old English.