! -- factorial

Synopsis

Usage:

n!
Inputs:
- n, an integer
Outputs:
- an integer, n factorial, 1*2*3*...*n.

Description

i1 : 30!

o1 = 265252859812191058636308480000000

i2 : 30.!

o2 = 2.65252859812191e32

o2 : RR (of precision 53)

i3 : 30.01!

o3 = 2.74475749473282e32

o3 : RR (of precision 53)

Ways to use symbol ! :

Constant !
QQ !
RR !
ZZ !

For the programmer

The object ! is a keyword.

This operator may be used as a postfix unary operator in an expression like x!. The user may install a method for handling such expressions with code such as

         X !   := (x) -> ...

where X is the class of x.