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

Related Information: You can use the “-F Option” on page 107 to select a different
configuration file, a specific stanza in the configuration file,
or both.
Determining Which Level of XL Fortran Is Installed
Sometimes, you may not be sure which level of XL Fortran is installed on a
particular machine. You would need to know this information before contacting
software support.
To check whether the latest level of the product has been installed through the
system installation procedure, issue the command:
lslpp -h "*xlf*"
The result includes the version, release, modification, and fix level of the compiler
image installed on the system.
To check the level of the compiler executable itself, issue the command:
what /usr/lpp/xlf/bin/xlfentry
If the compiler is installed in a different directory, use the appropriate path name
for the xlfentry file.
You can also use the -qversion compiler option to see the version and release for
the compiler.
Upgrading to XL Fortran Version 9
Here is some advice to help make the transition from an earlier version of the XL
Fortran compiler as fast and simple as possible.
Things to Note in XL Fortran Version 9
Because XL Fortran Version 9.1 is highly compatible with XL Fortran Versions 8
through 3 inclusive, most of the advice in this section applies to upgrades from
Version 2, or earlier levels of XL Fortran.
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24 XL Fortran Enterprise Edition for AIX : User’s Guide
The xlf90, xlf90_r, and xlf90_r7 commands provide Fortran 90 conformance, and
the xlf95, xlf95_r, and xlf95_r7 commands provide Fortran 95 conformance.
However, these commands may cause some problems with existing FORTRAN
77 programs. The xlf, xlf_r, xlf_r7, f77, and fort77 commands avoid some of
these problems by keeping the old behavior wherever possible.
Fortran 90 introduced the idea of kind parameters for types. Except for the types
complex and character, XL Fortran uses numeric kind parameters that
correspond to the lengths of the types. For the type complex, the kind parameter
is equal to the length of the real portion, which is half of the overall length. For
the type character, the kind parameter is equal to the number of bytes that are
required to represent each character, and this value is 1. A FORTRAN 77
declaration that is written using the * extension for length specifiers can now be
rewritten with a kind parameter:
INTEGER*4 X ! F77 notation with extension.
INTEGER(4) X ! F90 standard notation.
COMPLEX*8 Y ! *n becomes (n) for all types except
COMPLEX(4) Y ! COMPLEX, where the value is halved.
This new form is the one we use consistently throughout the XL Fortran
manuals.