# Letters and Letter‐like Forms

Greek Letters | Units and Letter‐like Mathematical Symbols |

Variants of English Letters | Shapes, Icons, and Geometrical Constructs |

Formal Symbols | Textual Elements |

Hebrew Letters | Extended Latin Letters |

## 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 built‐in 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 built‐in meaning, combinations such as or have no built‐in 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 built‐in 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 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 will not.

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, 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 | |

\[ScriptA] – \[ScriptZ] | EscscaEsc – EscsczEsc | lowercase script letters |

EscscAEsc – EscscZEsc | uppercase script letters | |

\[GothicA] – \[GothicZ] | 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.

Formal symbols are Protected, so they cannot be accidentally assigned a value.

Specific values for formal symbols can be substituted using replacement rules.

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.

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.

It is possible to define custom typesetting rules for formal symbols.

In[84]:= |

In[87]:= |

## Hebrew Letters

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 letter‐like 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 (\[Mu]), (\[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.

## Shapes, Icons, and Geometrical Constructs

Shapes are most often used as "dingbats" to emphasize pieces of text. But the Wolfram Language 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 the Wolfram Language as operators rather than letter‐like forms.

Notation for geometrical constructs.

Since the Wolfram Language treats characters like as letter‐like 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.

## Extended Latin Letters

The Wolfram Language supports all the characters commonly used in Western European languages based on Latin scripts.

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.

You can make additional characters by explicitly adding diacritical marks yourself.

char Ctrl+& mark Ctrl+Space | add a mark above a character |

char Ctrl+$ mark Ctrl+Space | add a mark below a character |

Adding marks above and below characters.

form | alias | full name | |

' | (keyboard character) | \[RawQuote] | acute accent |

′ | Esc | \[Prime] | acute accent |

` | (keyboard character) | \[RawBackquote] | grave accent |

‵ | Esc`Esc | \[ReversePrime] | grave accent |

. . | (keyboard characters) | umlaut or diaeresis | |

^ | (keyboard character) | \[RawWedge] | circumflex or hat |

◦ | EscesciEsc | \[EmptySmallCircle] | ring |

. | (keyboard character) | \[RawDot] | dot |

~ | (keyboard character) | \[RawTilde] | tilde |

_ | (keyboard character) | \[RawUnderscore] | bar or macron |

ˇ | EschcEsc | \[Hacek] | hacek or check |

˘ | EscbvEsc | \[Breve] | breve |

| EscdbvEsc | \[DownBreve] | tie accent |

″ | Esc | \[DoublePrime] | long umlaut |

¸ | EsccdEsc | \[Cedilla] | cedilla |

Diacritical marks to add to characters.