Section 11,1: ABS

 ABS (number)

 A function that returns the absolute value of the argument.  The
 absolute value of a complex number, (X,Y), is the real value:
    (X**2 + Y**2)**(1/2).

 +------+---------+----------+------------+-------------+        
 | Args | Generic | Specific |  Argument  | Result Type |
 +------+---------+----------+------------+-------------+
 |  1   |  ABS    |  --      | INTEGER*1  | INTEGER*1   |
 |      |         | IIABS    | INTEGER*2  | INTEGER*2   |
 |      |         | JIABS    | INTEGER*4  | INTEGER*4   |
 |      |see note | KIABS    | INTEGER*8  | INTEGER*8   |
 |      |         | ABS      | REAL*4     | REAL*4      |
 |      |         | DABS     | REAL*8     | REAL*8      |
 |      |see note | QABS     | REAL*16    | REAL*16     |
 |      |         | CABS     | COMPLEX*8  | REAL*4      |
 |      |         | CDABS    | COMPLEX*16 | REAL*8      |
 |      |         | ZABS     | COMPLEX*16 | REAL*8      |
 +------+---------+----------+------------+-------------+

 NOTE: KIABS is only available on AXP systems.
       QABS is not available in DEC Fortran.

 See also the IABS intrinsic function.