Using the Generic Mapping Tools From Within the MATLAB, Octave and Julia Computing Environments

The Generic Mapping Tools (GMT) is a widely used software infrastructure tool set for analyzing and displaying geoscience data. Its power to analyze and process data and produce publication-quality graphics has made it one of several standard processing toolsets used by a large segment of the Earth and Ocean Sciences. GMT's strengths lie in superior publication-quality vector graphics, geodetic-quality map projections, robust data processing algorithms scalable to enormous data sets, and ability to run under all common operating systems. The GMT tool chest offers over 120 modules sharing a common set of command options, file structures, and documentation. GMT modules are command line tools that accept input and write output, and this design allows users to write scripts in which one module's output becomes another module's input, creating highly customized GMT workflows. With the release of GMT 5, these modules are high-level functions with a C API, potentially allowing users access to high-level GMT capabilities from any programmable environment. Many scientists who use GMT also use other computational tools, such as MATLAB® and its clone Octave. We have built a MATLAB/Octave interface on top of the GMT 5 C API. Thus, MATLAB or Octave now has full access to all GMT modules as well as fundamental input/output of GMT data objects via a MEX function. Internally, the GMT/MATLAB C API defines six high-level composite data objects that handle input and output of data via individual GMT modules. These are data tables, grids, text tables (text/data mixed records), color palette tables, raster images (1-4 color bands), and PostScript. The API is responsible for translating between the six GMT objects and the corresponding native MATLAB objects. References to data arrays are passed if transposing of matrices is not required. The GMT and MATLAB/Octave combination is extremely flexible, letting the user harvest the general numerical and graphical capabilities of both systems, and represents a giant step forward in interoperability between GMT and other software package. We will present examples of the symbiotic benefits of combining these platforms. Two other extensions are also in the works: a nearly finished Julia wrapper and an embryonic Python module. Publication supported by FCT- project UID/GEO/50019/2013 - Instituto D. Luiz