An External function () interfaces with other external functions written in the C language (using a native C function or, through a wrapper function, interfacing with source code written in, for example, Fortran). You can use those functions as any other functions defined in COMSOL Multiphysics. For example, use it for a user-created shared library (depending on the platform, a DLL, .so, or .dylib file).

Enter a Library path and name (the complete network path), or click Browse to locate a library to import. You can also click the downward arrow beside the Browse button and choose Browse From () to open the fullscreen Select File window. Click the downward arrow for the File Location Actions menu () to choose Show in Auxiliary Data () to move to the row for this file in the Auxiliary Data window, Copy File Location (), and (if you have copied a file location) Paste File Location ().

For each row in the table, enter a Function name (myfun, for example) and a space-separated or comma-separated list of the names of its input Arguments (x y, for example).

Enter a value in the Initialization data field. The value is sent to the library when it is loaded. Select the Thread safe check box to declare that the function is a thread-safe pure function (that is, a function that always returns the same results using the same input argument values and that does not have any side effects or output). Select this check box to improve performance.