XL Fortran Enterprise Edition for AIX : User's Guide - IBM

Table 1. Potential Problems Migrating Programs to XL Fortran Version 9 (continued). The
column on the right shows which problems you can avoid by using the xlf or f77 command.
Potential Problem Solution or Workaround xlf Avoids?
SIGN(A,B) now returns -|A| when B=-0.0.
Prior to XL Fortran Version 7.1, it returned
|A|.
A minus sign is printed for a negative zero
in formatted output. A minus sign is
printed for negative values that have an
outputted form of zero (that is, in the case
where trailing non-zero digits are truncated
from the output so that the resulting output
looks like zero). Prior to XL Fortran Version
7.1, minus signs were not printed in these
situations.
This behavior conforms with
the Fortran 95 standard and
is consistent with the IEEE
standard for binary
floating-point arithmetic. It
occurs because the
-qxlf90=signedzero option is
turned on. Turn it off, or
specify a command that does
not use this option by
default.
This behavior conforms with
the Fortran 95 standard and
occurs because the
-qxlf90=signedzero option is
turned on. Turn it off, or
specify a command that does
not use this option by
default.
U
U
Related Information:
v “Compiling for Specific Architectures” on page 39
v “Setting Run-Time Options” on page 51
v “-qalias Option” on page 122
v “-qextern Option” on page 157
v “-qposition Option” on page 219
v “-qsave Option” on page 228
v “-qxlf77 Option” on page 261
Running Two Levels of XL Fortran
It is possible for two different levels of the XL Fortran compiler to coexist on one
system. This allows you to invoke one level by default and to invoke the other one
whenever you explicitly choose to.
To do this, consult the XL Fortran Enterprise Edition for AIX Installation Guide for
details.
28 XL Fortran Enterprise Edition for AIX : User’s Guide