Section 11,33: IABS

 IABS (number)

 A function that returns the absolute value of the argument.  The
 absolute value of a complex number, (X,Y), is the real value
 SQRT(X**2 + Y**2).

 +------+---------+----------+------------+-------------+        
 | Args | Generic | Specific |  Argument  | Result Type |
 +------+---------+----------+------------+-------------+
 |  1   |  IABS   |  --      | INTEGER*1  | INTEGER*1   |
 |      |         | IIABS    | INTEGER*2  | INTEGER*2   |
 |      |         | JIABS    | INTEGER*4  | INTEGER*4   |
 |      |see note | KIABS    | INTEGER*8  | INTEGER*8   |
 +------+---------+----------+------------+-------------+

 NOTE: KIABS is only available on AXP systems.
 See also the ABS intrinsic function.