Report on Fortran

Report submitted to the BCS Technical Board, December 1999

Introduction
In recent years the BCS Fortran Specialist Group has confined itself to supporting special events and to providing electronic information infrastructure and has not held ordinary meetings other than the annual general meeting. This is because many of the reasons for holding the actively supported meetings of the 1970s and 1980s have been superseded by electronic communication, that is by email lists, newsgroups and information distributed from web sites.

Electronic Communication
The Fortran Specialist Group has its own email list and its own web site (URL: http://www.fortran.bcs.org/). There is an active newsgroup for Fortran technical matters (comp.lang.fortran) and an active email discussion list (comp-fortran-90@mailbase.ac.uk) which although based in the UK is accessed by Fortran users world wide. There are a good number of Fortran-related web sites: many of them are linked directly or indirectly from URL: www.fortran.com.

There is a file, last updated in September 2004, listing available compilers, text books and courses at URL: http://www.fortran.com/metcalf.htm. (See also the link to more Fortran resources at the bottom of this page)

Fortran Languages
Fortran 90 compilers have been available since 1991. Fortran 95 was a relatively minor upgrade to the ISO standard and was approved in 1997. A number of compilers are available. Apart from five extremely minor, rare instances, Fortran 90 was upwards compatible from Fortran 77. There was therefore no need to adapt programs to run with new compilers and there is now little need to retain Fortran 77 compilers in service unless vendor-specific language extensions are needed.

For historical compatibility Fortran 90/95 thus has a great deal of redundancy, with features designed before the structured programming revolution of the early 1970s retained alongside more modern, elegant and expressive features. When Fortran 90/95 is taught to newcomers, it is possible to ignore the old and concentrate on the new. It is noticeable that modern undergraduates and postgraduates easily accept concepts which were considered difficult ten years ago. To accommodate Fortran as a teaching language, two suppliers have designed subsets of Fortran, known as ELF and F, and corresponding processors and text books exist; details are available via the URLs given above.

There is also the language HPF - High Performance Fortran. This is a development of the language for use on high performance computers by means of adding directives to standard Fortran using the syntax of comments. Thus a standard-conforming compiler can still process an HPF program.

Fortran Standards
The main language is known as Part 1 of the Fortran Standard and to be standard-conforming implies conformance to part 1. There is also Part 2, which provides varying length string facilities in a standard manner, and Part 3, which specifies conditional compilation facilities. Both parts 2 and 3 are optional.

There are also two ISO Technical Reports on Fortran, on floating point exception handling and on enhanced data types respectively. These are a form of beta test standard. They specify facilities which are wanted urgently and which are expected to be in the next edition of the standard, unless serious deficiencies are found with them at the beta test stage.

The home page of the ISO working group on Fortran is at http://www.nag.co.uk/sc22wg5/ from where further information may be obtained.

Fortran Standard Development
During 1995 and 1996 countries participating in the ISO Working Group on Fortran, whose full title is ISO IEC/JTC1/SC22/WG5, collected requirements for the next revision. Whereas Fortran 95 had been a minor revision of Fortran 90, Fortran 2000 was to have more wide-ranging extensions.

The system of working for the past ten years has been that the ISO group specifies the requirements and it delegates detailed development to 'development bodies', which are typically but not necessarily based in one country for practical reasons. The 'primary development body' so far has always been the US NCITS committee J3, better known under its former name X3J3. Development bodies for other projects, such as for the technical reports and for the subsidiary parts, have been subsets of WG5 members, generally with project editors from the UK. About seven countries normally send participants to WG5 meetings. A few other countries, notably Russia, participate by email.

When Fortran 2000 development started, it was envisaged that the first draft would be available in August 2000. ISO procedures for voting and revising then gave a target date for formal approval target date of November 2002. At the meeting in June 1999, WG5 reluctantly acceded to a request from J3 to extend both target dates by two years. This was because the load on J3 of both development of Fortran 2000 and interpretation work on Fortran 95 was exceeding the resources available.

UK Fortran Panel
The UK Fortran Panel is a subsidiary panel of BSI committee IST/5, Programming Languages. There have been no specifically British Fortran-related standards for some time. As programming languages are essentially international in nature, the policy of IST/5 is to support only ISO standards and to have the UK play a full role in their development. ISO rules are such that only those nominated by national bodies such as BSI can take part in ISO meetings.

Most members of the UK Fortran panel are also members of the Fortran Specialist Group. Several members of the specialist group are, or have been at various times, also members of IST/5 although they have typically been nominated by JISC rather than by the BCS.

The UK plays a full part in WG5. The present and previous convenors have both been from the UK (and both are FSG members). At WG5 meetings the UK delegation is typically the largest or second largest, alternating with the US, and as noted above UK members are active as project editors or subgroup convenors or play other active roles.

Thus although the Fortran Specialist Group per se is not holding frequent meetings, its members are unobtrusively busy on Fortran matters.

David Muxworthy
Secretary, BCS Fortran Specialist Group (and BSI Fortran Convenor)
6 December 1999

Links updated August 2001, April 2006 and October 2009.


Details of current Fortran standardization activities can be found in WG5's own World Wide Web pages.


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