Psi function
# Psi function

Psi function can refer, in mathematics, to

* the ordinal collapsing function $\psi (\alpha )$
* the Dedekind psi function $\psi (n)$
* the Chebyshev function $\psi (x)$
* the polygamma function $\psi ^{m}(z)$ or its special cases
   * the digamma function $\psi (z)$
   * the trigamma function $\psi ^{1}(z)$

and in physics to

