Introduction |
Fortran is a general purpose programming language, mainly
intended for mathematical computations in science applications (e.g. physics).
Fortran is an acronym for FORmula TRANslation, and was originally capitalized as
FORTRAN. However, following the current trend to only capitalize the first
letter in acronyms, we will call it Fortran.
A D V E R T I S E M E N T
Fortran was the first high-level
programming language. The work on Fortran started in the 1950's at IBM and there
have been many versions since. By convention, a Fortran version is denoted by
the last two digits of the year the standard was proposed. Thus we have Fortran
66, Fortran 77 and Fortran 90 (95).
The most common Fortran version
today is still Fortran 77, although Fortran 90 is growing in popularity. Fortran
95 is a revised version of Fortran 90 which is expected to be approved by ANSI
soon (1996). There are also several versions of Fortran aimed at parallel
computers. The most important one is High Performance Fortran (HPF), which is a
de-facto standard.
Users should be aware that most
Fortran 77 compilers allow a superset of Fortran 77, i.e. they allow
non-standard extensions. In this tutorial we will emphasize standard ANSI
Fortran 77.
Fortran is the dominant
programming language used in scientific applications. It is therefore important
for physics (or engineering) students to be able to read and modify Fortran
code. From time to time, so-called experts predict that Fortran will rapidly
fade in popularity and soon become extinct. This may actually happen as C (or
C++) is rapidly growing in popularity. However, previous predictions of the
downfall of Fortran have always been wrong. Fortran is the most enduring
computer programming language in history. One of the main reasons Fortran has
survived and will survive is software inertia. Once a company has spent
many people-years and perhaps millions of dollars on a software product, it is
unlikely to try to translate the software to a different language. Reliable
software translation is a very difficult task and there�s 40 years of Fortran
code to replace!
A major advantage Fortran has is that it is standardized
by ANSI (American National Standards Institute) and ISO (International Standards
Organization). Consequently, if your program is written in ANSI Fortran 77 then
it will run on any computer that has a Fortran 77 compiler. Thus, Fortran
programs are portable across computer platforms
