Pi

Function: Pi
Section: transcendental
C-Name: mppi
Prototype: p
Help: Pi=Pi(): the constant pi, with current precision.
Description:
 ():real:prec        mppi($prec)
Doc: the constant $\pi$ ($3.14159\cdots$). Note that \kbd{Pi} is one of the few
 reserved names which cannot be used for user variables.