abs(3M)

NAME
     ABS, IABS, DABS, CABS, CDABS - Computes absolute value

SYNOPSIS
     UNICOS and UNICOS/mk systems:

     ABS ([A=]a)
     IABS ([A=]a)
     DABS ([A=]a)
     CABS ([A=]a)

     UNICOS and IRIX systems:
     CDABS ([A=]a)

IMPLEMENTATION
     UNICOS, UNICOS/mk, and IRIX systems

STANDARDS
     Fortran 90
     CDABS is a compiler extension to Fortran 90

DESCRIPTION
     ABS is the generic function name.  ABS, IABS, DABS, and CABS are
     intrinsic and are elemental functions for the CF90 compiler.

     The entry point CDABS is provided for support in other languages.  It
     is not recognized as an intrinsic function; therefore, you must use
     the CDIR$ VFUNCTION directive to allow vectorization.

     These functions evaluate as follows:  y = |x|, except for CABS and
     CDABS, which evaluate the following:
                  2     2 1/2
          y = |(x   + x  )   |'
                 r     i
   CF90
     CDABS is called implicitly by the Fortran 90 compiler as a result of a
     generic ABS call with a complex double argument.

   CAL Register Usage (Cray Research Systems Only)
     Scalar IABS:  IABS% (call-by-register)
          on entry   (S1) = argument
          on exit    (S1) = result

     Scalar DABS:  DABS% (call-by-register)
          on entry   (S1) and (S2) = argument
          on exit    (S1) and (S2) = result

     Scalar CABS:  CABS% (call-by-register)
          on entry   (S1) and (S2) = argument
          on exit    (S1) = result

     Vector CABS:  %CABS% (call-by-register)
          on entry   (V1) = argument vector 1 (real part)
                     (V2) = argument vector 2 (imaginary part)
          on exit    (V1) = result vector

     Scalar CDABS:  CDABS% (call-by-register)
          on entry   (S1), (S2), (S3), (S4) = argument
          on exit    (S1), (S2) = result

     Vector CDABS:  %CDABS% (call-by-register)
          on entry   (V1), (V2), (V3), (V4) = argument vector
          on exit    (V1), (V2) = result vector

   Argument Ranges               2450
     infinity is approximately 10
                                                       308
     On UNICOS/mk systems, infinity is approximately 10

     ABS, IABS, DABS:

          |x| < infinity

     CABS, CDABS (CDABS is not available on UNICOS/mk systems):

          |x |, |x | < infinity
            r     i
NOTES
     CDABS is an outmoded routine for the CF90 compiler.  Refer to the
     Fortran Language Reference Manual, Volume 3, publication SR-3905, for
     information about outmoded features and their preferred standard
     alternatives.

     The name of the ABS, IABS, DABS, and CABS intrinsic can be passed as
     an argument.  The name of the CDABS intrinsic cannot be passed as an
     argument.

RETURN VALUES
     ABS returns the real absolute value of its real argument.

     IABS returns the integer absolute value of its integer argument.

     DABS returns the double-precision absolute value of its
     double-precision argument.

     CABS returns the absolute value of its complex argument as a real
     number.

     CDABS returns the absolute value of its complex double-precision
     argument as a double-precision number.

     When the correct value would overflow, CABS and CDABS abort with a
     floating-point error.

     On CRAY T90 systems that support IEEE arithmetic, the following return
     values occur:

     ABS(x):

          |x| = infinity, result is infinity

          x =  NaN, result is NaN

     CABS(x):

          x or y = NaN, result is NaN

          |x| = infinity and y is not NaN, result is infinity

          |y| = inf and x is not NaN, result is infinity

     When overflow occurs for good input, infinity is returned.

SEE ALSO
     Intrinsic Procedures Reference Manual, publication SR-2138, for the
     printed version of this man page.