Epsilon

Epsilon (uppercase Ε, lowercase ε or lunate ϵ; Greek: Έψιλον) is the fifth letter of the Greek alphabet, corresponding phonetically to a close-mid front unrounded vowel /e/. In the system of Greek numerals it has the value five. It was derived from the Phoenician letter He . Letters that arose from epsilon include the Roman E, Ë and Ɛ, and Cyrillic Е, È, Ё, Є and Э.

The name of the letter was originally εἶ (Ancient Greek: [êː]), but the name was changed to ἒ ψιλόν (e psilon "simple e") in the Middle Ages to distinguish the letter from the digraph αι, a former diphthong that had come to be pronounced the same as epsilon.

In essence, the uppercase form of epsilon looks identical to Latin E. The lowercase version has two typographical variants, both inherited from medieval Greek handwriting. One, the most common in modern typography and inherited from medieval minuscule, looks like a reversed "3". The other, also known as lunate or uncial epsilon and inherited from earlier uncial writing, looks like a semicircle crossed by a horizontal bar. While in normal typography these are just alternative font variants, they may have different meanings as mathematical symbols. Computer systems therefore offer distinct encodings for them. In Unicode, the character U+03F5 "Greek lunate epsilon symbol" (ϵ) is provided specifically for the lunate form. In TeX, \epsilon () denotes the lunate form, while \varepsilon () denotes the inverted-3 form.

Epsilon (text editor)

Epsilon is a programmer's text editor modelled after Emacs. It resembles Emacs not only in its default keybindings and layout, but also in the fact that it has a Turing-complete extension language in which much of its functionality is implemented. Unlike Emacs, Epsilon's extension language, EEL (Epsilon Extension Language) is a dialect of C rather than a dialect of Lisp. Epsilon runs on DOS, Microsoft Windows, Linux, FreeBSD, Mac OS X and OS/2.

Epsilon is a commercial product sold by Lugaru Software. It was first released in 1984, long before Emacs was available on personal computers, and modestly priced, so it provided an attractive alternative to the usual DOS editors for those accustomed to Emacs. It was also the first DOS based editor to allow editing of files that were larger than available RAM.

Epsilon supports Unicode but does not display characters outside the BMP and cannot presently handle right-to-left scripts. It can convert among dozens of character encodings.

Epsilon (rocket)

The Epsilon rocket (イプシロンロケット, Ipushiron roketto) (formerly Advanced Solid Rocket) is a Japanese solid-fuel rocket designed to launch scientific satellites. It is a follow-on project to the larger and more expensive M-V rocket which was retired in 2006. The Japan Aerospace Exploration Agency (JAXA) began developing the Epsilon in 2007. It is designed to be capable of placing a 1.2 tonne payload into low Earth orbit.

Vehicle description

The development aim is to reduce costs compared to the US$70 million launch cost of an M-V. The Epsilon costs US$38 million (£23m) per launch, which is half the cost of its predecessor. Development expenditures by JAXA exceeded US$200 million.

To reduce the cost per launch the Epsilon uses the existing SRB-A3 as a solid rocket booster on the H-IIA rocket as its first stage. Existing M-V upper stages will be used for the second and third stages, with an optional fourth stage available for launches to higher orbits. The J-1 rocket, which was developed during the 1990s, but abandoned after just one launch, used a similar design concept, with an H-II booster and Mu-3S-II upper stages.