Fortran is a high-level programming language used mainly in scientific and mathematical computing. Modern versions of Fortran have many features of interpreted matrix languages such as Matlab, e.g., vector notation, and built-in vector and matrix operators. The language dates back to 1957; the most used standards are Fortran 77 and Fortran 90/95, with Fortran 2003 and Fortran 2008 being the more recent revisions (as of 2014).

Fortran is available on all popular platforms, and there is a number of compilers (see comparison), such as:

GCC/GFortran: GFortran is part of the GNU Compiler Collection (GCC) and is freely available for download on all popular platforms and operating systems; it is installed on all Northwestern Linux servers, including SSCC, Quest, and Skew. The launch command is gfortran.

Intel FortranIntel Fortran is available from Intel, both as standalone software and as a part of the Intel Parallel Studio, which also includes Intel C and C++ compilers, as well as some parallelization tools and libraries. It is highly optimized for code performance, particularly on Intel processors. It is installed on SSCC, Quest, and KDC. Intel compilers integrate with the Microsoft Visual Studio IDE on Windows and with XCode on Mac OS.

PGI Fortran: PGI Fortran is available for Windows, Mac, and Linux from The Portland Group, together with PGI C, C++, and other tools. PGI compilers also include functionality to easily adapt code for running on certain GPU's (video cards) for potentially substantial speed-ups (see example). The Mac version is free to download for personal use through the Free PGI program, and the Linux version is installed on SSCC.

Sun Fortran: Sun Fortran is available for SunOS systems, such as WRDS. The commands are f77f90, and f95.

Learning Fortran Using Fortran with Other Languages Fortran Libraries Other References