Phi
Phi () is a letter in the Greek alphabet. It is often used to represent the constant
. (The Greek letter tau (
) was also used in pre-Renaissance times.)
Contents
[hide]Use
appears in a variety of different mathematical contexts: it is the limit of the ratio of successive terms of the Fibonacci sequence, as well as the positive solution of the quadratic equation
.
Golden ratio
is also known as the Golden Ratio. It was commonly believed by the Greeks to be the most aesthetically pleasing ratio between side lengths in a rectangle. The Golden Rectangle is a rectangle with side lengths of 1 and
; it has a number of interesting properties.
The first fifteen digits of in decimal representation are
Other useages
is also commonly used to represent Euler's totient function.
appears in many uses, including Physics, Biology and many others.