PROGRAMMING LANGUAGES: August 2017

FORTRAN

In 1957, the first of the major languages appeared in the form of FORTRAN. Its name stands for FORmula TRANslating system. The language was designed at IBM for scientific computing. The components were very simple, and provided the programmer with low-level

Fortran (formerly FORTRAN, derived from "Formula Translation") is a general-purpose, imperative programming language that is especially suited to numeric computation and scientific computing. Originally developed by IBM in the 1950s for scientific and engineering applications, Fortran came to dominate this area of programming early on and has been in continuous use for over half a century in computationally intensive areas such as numerical weather prediction, finite element analysis, computational fluid dynamics, computational physics, crystallography and computational chemistry. It is a popular language for high-performance computing^[4] and is used for programs that benchmark and rank the world's fastest supercomputers.^[5]

Fortran encompasses a lineage of versions, each of which evolved to add extensions to the language while usually retaining compatibility with prior versions. Successive versions have added support for structured programming and processing of character-based data (FORTRAN 77), array programming, modular programming and generic programming (Fortran 90), high performance Fortran (Fortran 95), object-oriented programming (Fortran 2003) and concurrent programming (Fortran 2008).access to the computers innards.

PROGRAMS IN FORTRAN

The following Fortran code examples or sample programs show different situations depending on the compiler. The first set of examples are for the Fortran II, IV, and 77 compilers. The remaining examples can be compiled and run with any newer standard Fortran compiler (see the end of the main Fortran article for lists of compilers). By convention most contemporary Fortran compilers select the language standard to use during compilation based on source code file name suffix: FORTRAN 77 for .f (or the less common .for), Fortran 90 for.f90, Fortran 95 for.f95. Other standards, if supported, may be selected manually with a command line option.

FORTRAN II, IV, and 77 compilers

NOTE: Before FORTRAN 90, most FORTRAN compilers enforced fixed-format source code, a carryover from comments must begin with a * or C or ! in column 1

statement labels must occur in columns 1-5
continuation lines must have a non-blank character in column 6
statements must start in column 7
the line-length may be limited to 72 characters (derived from the 80-byte width of a punch-card, with last 8 characters reserved for (optional) sequence numbers)

If errors are produced when you compile your FORTRAN code, first check the column alignment. Some compilers also offer free form source by using a compiler flag

Area Of a Triangle program

Simple Fortran II program

One data card input

If one of the input values is zero, then the program will end with an error code of "1" in the job control card listing following the execution of the program. Normal output will be one line printed with A, B, C, and AREA. No specific units are stated.

C AREA OF A TRIANGLE - HERON'S FORMULA
C INPUT - CARD READER UNIT 5, INTEGER INPUT
C OUTPUT - LINE PRINTER UNIT 6, REAL OUTPUT
C INPUT ERROR DISPLAY ERROR OUTPUT CODE 1 IN JOB CONTROL LISTING
      INTEGER A,B,C
      READ(5,501) A,B,C
  501 FORMAT(3I5)
      IF(A.EQ.0 .OR. B.EQ.0 .OR. C.EQ.0) STOP 1
      S = (A + B + C) / 2.0
      AREA = SQRT( S * (S - A) * (S - B) * (S - C) )
      WRITE(6,601) A,B,C,AREA
  601 FORMAT(4H A= ,I5,5H  B= ,I5,5H  C= ,I5,8H  AREA= ,F10.2,
     $13H SQUARE UNITS)
      STOP
      END

Hello, World program

In keeping with computing tradition, the first example presented is a simple program to display the words "Hello, world" on the screen (or printer).

FORTRAN 66 (also FORTRAN IV)

 C     FORTRAN IV WAS ONE OF THE FIRST PROGRAMMING
 C     LANGUAGES TO SUPPORT SOURCE COMMENTS
       WRITE (6,7)
     7 FORMAT(13H HELLO, WORLD)
       STOP
       END

USES OF FORTRAN

The main use of frotran is:
I've read that Fortran is still heavily used for scientific computing. For code already heavily invested in Fortran this makes sense to me.

Monday, 21 August 2017