Psi (letter)

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From Simple English Wikipedia, the free encyclopedia

Psi (uppercase/lowercase Ψ ψ) is the 23rd letter of the Greek alphabet. It is used to represent the "ps" sound in Ancient and Modern Greek. In the system of Greek numerals, it has a value of 700. Letters that came from it include Cyrillic Ѱ.

In mathematics, the uppercase is used as a variable for sets of sentences (in logic), and the lowercase is used to represent the sum of reciprocals of Fibonacci numbers.[1] Other applications include the polygamma function, the gamma function and the super golden ratio.[2]

Related pages


  1. "Greek/Hebrew/Latin-based Symbols in Mathematics". Math Vault. 2020-03-20. Retrieved 2020-10-07.
  2. "Psi Symbol in Greek Alphabet". Retrieved 2020-10-07.