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Explore the journey of Fortran from its inception in the 1950s to the modern era, witnessing its impact on scientific and military communities, the development of Fortran II to Fortran 95, and understanding key features like variable typing, program structure, and arithmetic operators in Fortran 77. Learn about Fortran's significance, challenges, and future outlook in the world of programming.
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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 • 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
Fortran II • 1958 • separate compilation of modules • Assembly modules could be “link-loaded” by Fortran modules
Fortran III • Never released to the public • Assembly could be injected right in the middle of Fortran code • Lost HLL advantages when this happened
Fortran IV • 1961 • Cleaned up Fortran II • Eliminated machine-dependent irregularities
Fortran 66 • 1962-66 ASA standardized Fortran • First HLL standard in the world
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
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
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
Understanding Fortran 77 • Arithmetic Operators • Evaluation Order • **, * /, + - (highest to lowest) • Spaces are ignored • Ex. -1.0/X + Y/Z**2 • ML cannot do this
Understanding Fortran 77 • Program Example
Understanding Fortran 77 • Programs • Written in Columns • Layout of punch cards • Columns: • Comments: • Denoted by a ‘C’ or a ‘*’ in the 1st column
Present Status • The Array Language • The abstract data type • Requirements
The Future • Release Date • Standards
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.”
Source • Michael Metcalf • Paris, 1999 September