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FORTRAN

FORTRAN. The History of Fortran. Before Fortran there was a dark computing abyss Assembly was the only prominent language Mostly due to extreme memory limitations. continued. 1954-57 an IBM team led by John Backus Nothing new Extremely efficient optimizing compiler. continued.

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FORTRAN

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  1. FORTRAN

  2. The History of Fortran • Before Fortran there was a dark computing abyss • Assembly was the only prominent language • Mostly due to extreme memory limitations

  3. continued • 1954-57 an IBM team led by John Backus • Nothing new • Extremely efficient optimizing compiler

  4. continued • The compiler was the key • The scientific and military communities adopted Fortran as a standard • Fortran required less skill to program in • Programs could be developed in much less time • NASA used Fortran extensively

  5. Fortran II • 1958 • separate compilation of modules • Assembly modules could be “link-loaded” by Fortran modules

  6. Fortran III • Never released to the public • Assembly could be injected right in the middle of Fortran code • Lost HLL advantages when this happened

  7. Fortran IV • 1961 • Cleaned up Fortran II • Eliminated machine-dependent irregularities

  8. Fortran 66 • 1962-66 ASA standardized Fortran • First HLL standard in the world

  9. More Fortran • Fortran 77 improved on 66 • 1978… Disaster • Fortran was caught up in political entanglements (Fortran Saga) • 1991 gave Fortran 90 • Competition had caught up by this time • Fortran 95 added minor improvements

  10. Understanding Fortran 77 • Constants • Strings denoted with ‘ & ’ • Not “ & ” • Integers are 1, 2, 3 • Real numbers are -123.4, (0.6x10-3), 7E-3 • Variable types • 1-6 Characters per variable • All uppercase • All begin with an Alphabetic letter

  11. Understanding Fortran 77 • Variable Typing • INTEGER, CHARACTER, REAL • Ex. INTEGER AGE, AGE5 • Ex. CHARACTER NAME • READ Statement • Data input • Ex. READ *, NAME, AGE • PRINT Statement • Print data on the screen • Ex. PRINT *, ‘Hello ‘, NAME • Assignment Operator • AGE5 = AGE + 5

  12. Understanding Fortran 77 • Arithmetic Operators • Evaluation Order • **, * /, + - (highest to lowest) • Spaces are ignored • Ex. -1.0/X + Y/Z**2 • ML cannot do this

  13. Understanding Fortran 77 • Program Example

  14. Understanding Fortran 77 • Programs • Written in Columns • Layout of punch cards • Columns: • Comments: • Denoted by a ‘C’ or a ‘*’ in the 1st column

  15. Present Status • The Array Language • The abstract data type • Requirements

  16. The Future • Release Date • Standards

  17. Quote • “Fortran is likely to remain into the next century as, at the very least, a special-purpose scientific and numerical language for large-scale, computing-intensive applications; strengthen especially by its array capabilities, will be one of a small range of widely-used languages in general use.”

  18. Source • Michael Metcalf • Paris, 1999 September

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