ϕ

See also: Φ, φ, and ɸ

ϕ U+03D5, ϕ GREEK PHI SYMBOL ← ϔ [U+03D4] Greek and Coptic ϖ → [U+03D6]

Translingual

Etymology

(mathematics): Named by mathematician Mark Barr after Ancient Greek Φειδίας (Pheidías) (Phidias), who supposedly used the golden ratio in his work.

Symbol

ϕ

1. (mathematics, geometry) The golden ratio, an irrational number with a value of approximately 1.618033988 which expresses the relationship that the sum of two quantities is to the larger quantity as the larger is to the smaller.
2. (Romic) A voiceless bilabial fricative (IPA: ɸ).

Usage notes

• The Unicode character U+03D5 GREEK PHI SYMBOL (ϕ) was intended for the mathematical symbol. It is not used at all for written Greek; instead, U+03C6 GREEK SMALL LETTER PHI (φ) should be used. Capitalization, for example, only works for the latter.
• The Unicode 3.0 standard (2002) states: "Fonts used primarily for Greek text may use either glyph form for U+03C6, but fonts that also intend to support technical use of the Greek letters should use the loopy form to ensure appropriate contrast with the straight form used for U+03D5." However, prior to Unicode 3.0 the glyphs on the Unicode chart were reversed, so that the alphabetic letter U+03C6 GREEK SMALL LETTER PHI (φ) was straight and the mathematical symbol U+03D5 GREEK PHI SYMBOL (ϕ) had a loop, and many fonts developed prior to 2002 copied the reversed glyph shapes. Independently of this, may write the golden ratio with either $\varphi$ (\phi or $\phi$ (\varphi) in LaTeX) .