mexFunction (C and Fortran)

Entry point to C/C++ or Fortran MEX-file

C Syntax

#include "mex.h"
void mexFunction(int nlhs, mxArray *plhs[], int nrhs, 
  const mxArray *prhs[])

Fortran Syntax

#include "fintrf.h"
subroutine mexFunction(nlhs, plhs, nrhs, prhs)
integer nlhs, nrhs
mwPointer plhs(*), prhs(*)



Number of expected output mxArrays


Array of pointers to the expected output mxArrays


Number of input mxArrays


Array of pointers to the input mxArrays. Do not modify any prhs values in your MEX-file. Changing the data in these read-only mxArrays can produce undesired side effects.


mexFunction is not a routine you call. Rather, mexFunction is the name of the gateway function in C (subroutine in Fortran) which every MEX-file requires. When you invoke a MEX-function, MATLAB® software finds and loads the corresponding MEX-file of the same name. MATLAB then searches for a symbol named mexFunction within the MEX-file. If it finds one, it calls the MEX-function using the address of the mexFunction symbol. MATLAB displays an error message if it cannot find a routine named mexFunction inside the MEX-file.

When you invoke a MEX-file, MATLAB automatically seeds nlhs, plhs, nrhs, and prhs with the caller's information. In the syntax of the MATLAB language, functions have the general form:

[a,b,c,...] = fun(d,e,f,...)

where the ... denotes more items of the same format. The a,b,c... are left-side output arguments, and the d,e,f... are right-side input arguments. The arguments nlhs and nrhs contain the number of left side and right side arguments, respectively. prhs is an array of mxArray pointers whose length is nrhs. plhs is an array whose length is nlhs, where your function must set pointers for the output mxArrays.


See the following examples in matlabroot/extern/examples/mex.

Was this topic helpful?