Introduction

Historical highlights

The GMT system was initiated in late 1987 at Lamont-Doherty Earth Observatory, Columbia University by graduate students Paul Wessel and Walter H. F. Smith. Version 1 was officially introduced to Lamont scientists in July 1988. GMT 1 migrated by word of mouth (and tape) to other institutions in the United States, UK, Japan, and France and attracted a small following. Paul took a Post-doctoral position at SOEST in December 1989 and continued the GMT development. Version 2.0 was released with an article in EOS, October 1991, and quickly spread worldwide. Version 3.0 in 1993 which was released with another article in EOS on August 15, 1995. A major upgrade to GMT 4.0 took place in Oct 2004. Finally, in 2013 we released the new GMT 5 series and we have updated this tutorial to reflect the changes in style and syntax. However, GMT 5 is generally backwards compatible with GMT 4 syntax. In October 2019 we released the current version GMT 6. GMT is used by tens of thousands of users worldwide in a broad range of disciplines.

Philosophy

GMT follows the UNIX philosophy in which complex tasks are broken down into smaller and more manageable components. Individual GMT modules are small, easy to maintain, and can be used as any other UNIX tool. GMT is written in the ANSI C programming language (very portable), is POSIX compliant, and is independent of hardware constraints (e.g., memory). GMT was deliberately written for command-line usage, not a windows environment, in order to maximize flexibility. We standardized early on to use PostScript output instead of other graphics formats. Apart from the built-in support for coastlines, GMT completely decouples data retrieval from the main GMT modules. GMT uses architecture-independent file formats.