Definitions

# e

[ee]
e, in mathematics, irrational number occurring widely in mathematics and science, approximately equal to the value 2.71828; it is the base of natural, or Naperian, logarithms. The number e is defined as the limit of the expression (1+1/n)n as n becomes infinitely large, orIn 1873 the French mathematician C. Hermite proved that e was transcendental, i.e., not a root of any algebraic equation; this proof constituted a great contribution to the growth of mathematics. The number e is also known as Euler's number, for Leonhard Euler, who discovered the famous formula e=-1, where i=-1, thus expressing the relationship between the numbers e, i, and π. The exponential function ex, often written exp(x), occurs in various applications ranging from statistics to nuclear physics.

See study by E. Maor (1994).

E is the fifth letter in the Latin alphabet. Its name in English is spelled e plural es or ees (also written E's, Es, e's, etc.). The letter E is the most commonly used letter in the Czech, Danish, Dutch, English, French, German, Hungarian, Latin, Norwegian, Spanish, and Swedish languages.

## History

Egyptian hieroglyph
q’
Proto-Semitic
H
Phoenician
H
Etruscan
E
Greek
Epsilon
Roman/Cyrillic
E
A28

E is derived from the Greek letter epsilon which is much the same in appearance (Ε, ε) and function. In etymology, the Semitic probably first represented a praying or calling human figure (hillul jubilation), and was probably based on a similar Egyptian hieroglyph that was pronounced and used quite differently. In Semitic, the letter represented /h/ (and /e/ in foreign words), in Greek became Εψιλον (Epsilon) with the value /e/. Etruscans and Romans followed this usage. Arising from the Great Vowel Shift, English usage is rather different, namely /iː/ (derived from /eː/ in "me" or "bee") whereas other words like "bed" are closer to Latin and other languages in usage.

## Usage

Like other Latin vowels, E came in a long and a short variety. Originally, the only difference was in length but later on, short e represented /ɛ/. In other languages that use the letter E or e, it represents various other phonetic values, sometimes with accents to indicate contrasts (e ê é è ë ē ĕ ě ẽ ė ẹ ę ẻ).

Digraphs starting with E are common in many languages to indicate diphthongs and monophthongs, such as EA or EE for /iː/ or /eɪ/ in English, EI for /aɪ/ in German, or EU for /ø/ in French or /ɔɪ/ in German.

At the end of a word, E is very often silent in English (silent e), where old noun inflections have been dropped, although even when silent at the end of a word it often causes vowels in the word to be pronounced as diphthongs, conventionally called long vowels (compare as a noun rat and as a verb rate).

The letter 'E' is the most common (or highest frequency) letter in the English language (starting off the typographer's phrase ETAOIN SHRDLU) and many other related languages, which has implications in both cryptography and data compression. This makes it a difficult and popular letter to use when writing lipograms. Ernest Vincent Wright's Gadsby (1939), is considered a "dreadful" novel, and that "at least part of Wright's narrative difficulties were caused by language restrictions imposed by the lack of E. Both Georges Perec's novel A Void (La Disparition) (1969) and its English translation by Gilbert Adair omit the letter E and are considered better works.

## Codes for computing

In Unicode the capital E is codepoint U+0045 and the lower case e is U+0065.

The ASCII code for capital E is 69 and for lowercase e is 101; or in binary 01000101 and 01100101, correspondingly.

The EBCDIC code for capital E is 197 and for lowercase e is 133.

The numeric character references in HTML and XML are "&#69;" and "&#101;" for upper and lower case respectively.