External Interfaces/API

Calling C and Fortran Programs from MATLAB

Although MATLAB^® is a complete, self-contained environment for programming and manipulating data, it is often useful to interact with data and programs external to the MATLAB environment. MATLAB provides an interface to external programs written in the C and Fortran languages. This interface is part of the MATLAB Application Program Interface, or API.

This section discusses the following topics:

• Introducing MEX-Files
• MATLAB Data
• Building MEX-Files
• Custom Building MEX-Files
• Troubleshooting
• Additional Information

For additional information and support in building your applications, see the Additional Information section of this chapter.

Note    In platform independent discussions that refer to directory paths, this book uses the UNIX convention. For example, a general reference to the mex directory is <matlab>/extern/examples/mex.

Introducing MEX-Files

You can call your own C or Fortran subroutines from MATLAB as if they were built-in functions. MATLAB callable C and Fortran programs are referred to as MEX-files. MEX-files are dynamically linked subroutines that the MATLAB interpreter can automatically load and execute.

MEX-files have several applications:

• Large pre-existing C and Fortran programs can be called from MATLAB without having to be rewritten as M-files.
• Bottleneck computations (usually for-loops) that do not run fast enough in MATLAB can be recoded in C or Fortran for efficiency.

MEX-files are not appropriate for all applications. MATLAB is a high-productivity system whose specialty is eliminating time-consuming, low-level programming in compiled languages like Fortran or C. In general, most programming should be done in MATLAB. Don't use the MEX facility unless your application requires it.

External Interfaces/API

Using MEX-Files