Psi (letter) (generalized) positional states of a qubit in a quantum computer. Psi is also used as the symbol for the polygamma function, defined by where formula_3 is the gamma function. The letters Ψ or ψ can also be a symbol for: These characters are used only as mathematical symbols. Stylized Greek text should be encoded using the normal Greek letters, with markup and formatting to indicate text style. Psi (letter) Psi (; uppercase ', lowercase '; "psi" ) is the 23rd letter of the Greek alphabet and has a numeric value of 700. In both Classical and Modern Greek, the letter
History of the Greek alphabet them from certain digraphs which had become homophonous, as follows: The letters of the alphabet were used in the system of Greek numerals. For this purpose the letters digamma and qoppa (but not san) were retained although they had gone out of general use, and the obscure letter sampi was added at the end of the alphabet. Digamma was often replaced in numerical use by stigma (Ϛ), originally a ligature of sigma and tau, or even the sequence sigma-tau (στ'). The Old Italic and Anatolian alphabets are, like the Greek alphabet, attested from the 8th century BC. It is unclear