Fortran

What Fortran is

Fortran is a programming language built for numerical work: the arithmetic-heavy computing that science and engineering depend on, where a problem arrives as a set of formulas and has to be reduced to long sequences of operations on numbers. The name is short for formula translation ^[1]. The programmer writes statements that resemble mathematical notation, and a separate program — the compiler — turns those statements into the instructions the machine actually executes. Fortran was developed from 1954 and commercially released in 1957 ^[1].

Why it was needed

In the early years of electronic computing a program was written in the machine's own instruction set. The programmer chose each storage location, moved each value, and arranged each operation by hand. The work was slow, easy to get wrong, and tied to one particular machine. In 1953 John Backus was given a budget to hire a small team to test the feasibility of a language that captured human intent ^[1]. Backus, the primary author of the language, described hand coding as hand-to-hand combat with the machine ^[1] — a phrase that conveys what the team was trying to escape.

The team and the machine

The group Backus assembled was small: David Sayre, Harlan Herrick, Lois Haibt, Robert Nelson, Roy Nutt, Sheldon Best, Richard Goldberg and Peter Sheridan ^[1]. Lois Haibt built the arithmetic expression analyzer, the part of the system that reads a formula and works out how its pieces must be evaluated; she was the only woman on the team ^[1].

Computer time was scarce. The team often worked at night, because that was the only way to get time on the IBM 704, which IBM calls the first mass-produced computer to use high-speed magnetic core memory ^[1]. The schedule slipped badly: what was supposed to be a six-month operation took three years ^[1].

What was released

In 1957 the IBM Mathematical Formula Translating System, or Fortran, debuted, and soon afterwards IBM made the first Fortran compiler available to IBM 704 users ^[1]. The compiler was an optimizing one — the first, in IBM's account ^[1]. Optimization means the compiler does not translate each statement in isolation and leave it at that; it examines the program as a whole and rewrites the arithmetic so that the machine reaches the same result with fewer operations. That mattered because the whole case for such a language rested on speed. Backus's team produced code that ran nearly as fast as anything crafted by hand ^[1]. If compiled code had been noticeably slower than hand-written code, no programmer would have had a reason to give up writing instructions directly; with speed preserved, the higher-level language was worth using.

Where it sits in the history

IBM describes Fortran as the first computer language standard and as having liberated computers from the exclusive realm of programmers ^[1]. The second half of that description is the more telling one: once a calculation could be written in something close to mathematical form and still run fast, the person who understood the problem no longer had to be the same person who understood the machine. By the mid-1960s Fortran had become the first national computing standard and was used in most major data centres in the United States and parts of Europe ^[1].