FORTRAN

1
FORTRAN

• History

2
FORTRAN - Interesting Facts

• FORTRAN is the oldest Language actively in use
  today.
• FORTRAN is still used for new software
  development in many scientific applications
• Many FORTRAN programs written 20-40 years ago are
  still in active use today!

3
FORTRAN - Early History

• Early 1950s
• Computers very slow
• Small memories - 15k typical
• Little or no operating system
• Programming done in machine/assembly language
• Idea of a high level translated language seemed
  impractical
• code generated would be slower
• code generated would be bigger

4
FORTRAN I

• Developed in 1954-1957
• IBM team lead by John W. Backus
• FORTRAN - FORmula TRANslator
• Designed to ease coding of mathematical algorithms

5
FORTRAN I

• Programmers skeptical at first
• Then advantages seen
• Easier, faster to program
• Programs are portable
• Programs can be maintained
• Program libraries build and shared
• Adopted by the scientific and military
  communities

6
FORTRAN II

• FORTRAN II (1958) was a significant improvement
• added the capability for separate compilation of
  program modules
• assembly language modules could also be 'linked
  loaded' with FORTRAN modules.

7
FORTRAN III

• FORTRAN III (1958) never released to the public
• it made it possible to use assembly language
  code right in the middle of FORTRAN code.
• Such "inlined" assembly code can be more
  efficient, but the advantages of an HLL are
  lost (e.g. portability, ease of use).

8
FORTRAN IV

• FORTRAN IV (1961) was a 'clean up' of FORTRAN II
• improved the implementation of the COMMON and
  EQUIVALENCE statements
• eliminated some machine-dependant language
  irregularities.

9
FORTRAN 66

• First HLL Standard
• Card oriented (as were previous versions)

10
FORTRAN 77Standard

• Added
• DO loops with a decreasing control variable
  (index).
• Block if statements IF ... THEN ... ELSE ...
  ENDIF (before F77 there were only IF GOTO).
• Pretest of DO loops, before F77 DO loops were
  always executed at least once, so you had to add
  an IF GOTO before the loop.

11
FORTRAN 77

• Added
• CHARACTER data type (before characters were
  always stored inside INTEGER variables).
• Main program termination without a STOP statement

12
Fortran 90 standard

• Added
• Free format source code form (column independent)
• Modern control structures (CASE DO WHILE)
• Records (structures)
• Array notation (array sections, array operators,
  etc.)
• Dynamic memory allocation

13
Fortran 90 standard

• Added
• Dynamic memory allocation
• Derived types and operator overloading
• Keyword argument passing, INTENT (in, out, inout)
• Numeric precision and range control
• Modules
• Vector processing

14
FORTRAN 2000 Standard

• Expected about 2002