CERN Accelerating science

FORTRAN 77 to Fortran 90 Conversion

  Michael Metcalf IT/ASD

Although it has been decided that C++ is the way forward for future physics processing codes, there are nevertheless large numbers of FORTRAN 77 programs still in use. In the engineering field especially, this might well remain true for a very long time. However, the compilers available on all our platforms are now Fortran 90, and it is, in many respects, a pity not to take advantage of its features simply because the burden or bother of conversion is seen to be too great a hurdle. It is especially a pity for old codes that could do with a good clean-up, and those that could potentially take advantage of Fortran 90's array features.

Do not despair - help is at hand. We have available at CERN two conversion tools:

• convert: a simple program that converts the old FORTRAN 77 fixed source form to the new, optional, free source form. This program is available by "anonymous FTP" from asisftp.cern.ch in the directory dist as the file convert.f90. It contains its running instructions at the beginning.

• LOFT90: a full-blown, commercial product from NA Software of Liverpool. It is installed and freely available on the Meiko CS-2. This tool performs a complete syntactical conversion, including the replacement of many DO-loops by their array language equivalents.

LOFT90 has been tested at CERN on a large accelerator code, and the new version is somewhat faster, by about 7%, than the original FORTRAN 77 version. The use of LOFT90 has the incidental advantage that it removes many outmoded features, thus making new code fit to face future hardware/software combinations without being continuously hampered by language extensions that are no longer recognised.

To make life simple, I am prepared to offer help and advice to anyone wishing to use either of these products. Just ring me on 74427 or send an e-mail to Michael.Metcalf@cern.ch.

But hurry, this offer expires at the end of 1997!