
phi - the Euler phi function

Calling sequence:
phi(integer)

Parameter:

integer   --  integer not equal to 0

Overloading:

all

Summary:

phi calculates the Euler phi function of the argument integer, i.e. the
number of prime numbers smaller than abs(integer).

phi returns an error if the argument is a number but not an integer unequal
to 0. phi returns the call with evaluated arguments if the argument is not a
number. phi is a kernel function.

>>  phi(-7);

     6

