A.2.7 Calling Other Functions in Mex-Files

It is possible to call other Octave functions from within a mex-file using mexCallMATLAB. An example of the use of mexCallMATLAB can be see in the example below.

#include "mex.h"

void
mexFunction (int nlhs, mxArray *plhs[],
             int nrhs, const mxArray *prhs[])
{
  char *str;

  mexPrintf ("Starting file myfeval.mex\n");

  mexPrintf ("I have %d inputs and %d outputs\n", nrhs, nlhs);

  if (nrhs < 1 || ! mxIsChar (prhs[0]))
    mexErrMsgTxt ("ARG1 must be a function name");

  str = mxArrayToString (prhs[0]);

  mexPrintf ("I'm going to call the function %s\n", str);

  if (nlhs == 0)
    nlhs = 1;  // Octave's automatic 'ans' variable

  /* Cast prhs just to get rid of 'const' qualifier and stop compile warning */
  mexCallMATLAB (nlhs, plhs, nrhs-1, (mxArray**)prhs+1, str);

  mxFree (str);
}

If this code is in the file myfeval.c, and is compiled to myfeval.mex, then an example of its use is

a = myfeval ("sin", 1)
⇒ Starting file myfeval.mex
   I have 2 inputs and 1 outputs
   I'm going to call the interpreter function sin
   a =  0.84147

Note that it is not possible to use function handles within a mex-file.