Summary and Setup

This is a new lesson built with The Carpentries Workbench. It is currently in pre-alpha development by the Edinburgh Parallel Computing Centre, the National Centre for Atmospheric Science, the National Oceanography Centre, and the UK Met Office.

This course is aimed at users and developers who know how to program, but have little or no experience in Fortran, and those who may wish to have a refresher in Fortran.

Prerequisites

Learners must be familiar with the basic concepts of programming: variables, logic, flow of control, loops, functions and so on. No knowledge of Fortran is assumed. Previous programming experience might typically be in the context C/C++ or python. If you know no programming, we suggest this course on Fortran is not the place to start.

Fortran (a contraction of Formula Translation) was the first programming language to have a standard (in 1954), but has changed significantly over the years. More recent standards (the latest being Fortran 2018) come under the umbrella term “Modern Fortran”. Fortran retains very great significance in many areas of scientific and numerical computing, particularly for applications such as quantum chemistry, plasmas, and in numerical weather prediction and climate models.

This course provides an introduction to the basics of writing Fortran. It will cover basic syntax, variables, expressions and assignments, flow of control, and introductions to i/o and user-defined types. Common Fortran idioms are introduced and contrasted with those available in C-like languages; the course will try to focus on real usage rather than formal descriptions.

At the end of the course you should be able to understand many Fortran programs and be confident to start to write well-structured and portable Fortran. Fortran is a rather “large” language, so it is not possible to cover all its features in a two day course. Further elements of Fortran are discussed in the “Intermediate Modern Fortran” course.

The course requires a Fortran compiler, for which a local machine or laptop may be appropriate [1]. If you do not have access to a Fortran compiler, course training accounts on archer2 will be available which provide access to various compilers. Use of a text editor will be required (some may prefer an IDE, but we do not intend to consider or support IDEs).

[1] This may typically be GFortran, freely available as part of Gnu Compiler Collection (GCC). See e.g., Link to GFortran install page on fortran-lang

Data Sets

Download the zip file and unzip it to your Desktop or check out this git repository. This file contains data and skeleton code which we will use throughout the course.

Software Setup

Details

Before the start of the course please ensure that you have access to a Fortran compiler, and if necessary an account on archer2.

For details of how to log into an archer2 account, see archer2 quickstart guide link.

The default Fortran compiler on archer2 is the Cray Fortran compiler invoked using ftn. For example,

$ cd section1.01
$ ftn example1.f90

should generate an executable with the default name a.out.

If you are not taking this course on archer2 we recommend installing the GFortran compiler.

Text Editors and Integrated Development Environments (IDEs)

While Fortran files are plain text and can be edited with any plain text editor, it is recommened that you use an editor that is capable of syntax highlighting. Setup instructions for some editors are available below.

Emacs

Emacs is a cross-platform text editor available for Linux, MacOS, and Windows. Emacs applies syntax highlighting for most Fortran files, but additional file extensions, such as .X90 may be valid Fortran files but will not be picked up in Emacs f90-mode. This mode allows for tab-completion of Fortran statements and the addition of a drop-down menu that provides additional Fortran-related options.

Files can be manually set to f90-mode using M-x f90-mode, but file extensions can be added to your Emacs initialization file to ensure that these are recognised when opened. The format for this is

LISP 

(setq auto-mode-alist
      (append '(("\\.mf90" . f90-mode)
                ("\\.X90" . f90-mode)
        ) auto-mode-alist))