Function: eulerphi
Section: number_theoretical
C-Name: geulerphi
Prototype: G
Help: eulerphi(x): Euler's totient function of x.
Description:
 (int):int        eulerphi($1)
 (gen):gen        geulerphi($1)
Doc: Euler's $\phi$ (totient)\sidx{Euler totient function} function of $|x|$,
 in other words $|(\Z/x\Z)^*|$. Normally, $x$ must be of type integer, but
 the function accepts vector/matrices arguments, and is then applied
 componentwise.
Variant: For a \typ{INT} $x$, the variant
 \fun{GEN}{eulerphi}{GEN n} is also available.
