// mex_demo.c -- example of a dynamically linked function for Octave. // To compile this file, type the command // // mkoctfile --mex mex_demo.c // // from within Octave or from the shell prompt. This will create a file // called mex_demo.mex that can be loaded by Octave. To test the mex_demo.mex // file, start Octave and type the command // // d = mex_demo ("easy as", 1, 2, 3) // // at the Octave prompt. Octave should respond by printing // // Hello, world! // I have 4 inputs and 1 output // d = 1.2346 // Additional samples of code are in the examples directory of the Octave // distribution. See also the chapter External Code Interface in the // documentation. #include "mex.h" // Every user function should include "mex.h" which imports the basic set of // function prototypes necessary for dynamically linked functions. In // particular, it will declare mexFunction which is used by every function // which will be visible to Octave. A mexFunction is visible in Octave under // the name of the source code file without the extension. // The four arguments to mexFunction are: // 1) The number of return arguments (# of left-hand side args). // 2) An array of pointers to return arguments. // 3) The number of input arguments (# of right-hand side args). // 4) An array of pointers to input arguments. void mexFunction (int nlhs, mxArray *plhs[], int nrhs, const mxArray *prhs[]) { mexPrintf ("Hello, World!\n"); mexPrintf ("I have %d inputs and %d outputs\n", nrhs, nlhs); /* Demonstrate returning a matrix with a double value */ mxArray *v = mxCreateDoubleMatrix (1, 1, mxREAL); double *data = mxGetPr (v); *data = 1.23456789; plhs[0] = v; /* Return empty matrices for any other outputs */ int i; for (i = 1; i < nlhs; i++) plhs[i] = mxCreateDoubleMatrix (0, 0, mxREAL); }