Fortran/Why learn Fortran?

A 2020 supercomputer model of ocean velocity and sea surface temperature, generated with Fortran code. Fortran remains widely used for scientific programming, among other fields.

Fortran is a general purpose programming language mainly used by the scientific community. It is fast, portable and it has seamless handling of arrays and parallelism. It is one of the earliest high level programming languages, and many recognize the original versions which used punched cards to encode the programs. Its name is a contraction of FORmula TRANslation (old versions of the language are typically stylized as FORTRAN) and its creation marked the representation of mathematical expressions with more ease than lower level assembly language. It is still widely used today in numerical weather prediction, physical and chemical modelling, applied mathematics, and other high performance computing purposes. Fortran has a rich array of mathematical libraries and scientific codebases available. The newer standards continuously add modern functionality and are fully backward compatible.

This book is intended to help write code modern Fortran. Where appropriate the differences in usage between legacy versions and the modern standard will be highlighted as there is a significant code base written in older versions, especially FORTRAN 77.

When are other languages better?

Fortran is a very verbose, statically typed compiled language. It can take more time to write, compile and debug than other dynamically typed and interpreted languages. Therefore, many people have moved to languages (such as Python and Ruby) for productivity purposes.