FACT(<expN>)
 Evaluates the factorial of number.
 Returns <expN> product of all numbers between <expN> and 1.

 Returns INFINITY() if <expN> is 19 or greater, or zero if <expN>
 is less than or equal to zero.

 Because factorials grow very quickly, the results returned by
 this function lose their precision, and therefore their value,
 when <expN> reaches 19.  For this reason, the function returns
 INFINITY() when <expN> equals or exceeds this number.

 m_number = 15
 IF FACT( m_number ) = INFINITY()
    ? "Number is too large to compute its factorial"
 ELSE
    ? FACT( m_number )
 ENDIF


             Placed in the Public Domain by Tom Rettig Assoc.