entry point to c/c++ or Fortran MEX file

http://www.mathworks.com/access/helpdesk/help/techdoc/apiref/mexfunction.html
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
subroutine mexFunction(nlhs, plhs, nrhs, prhs)
integer*4 nlhs, nrhs
mwPointer plhs(*), prhs(*)
Arguments
nlhs
Number
of expected output mxArray
s
plhs
Array
of pointers to the expected output mxArray
s
nrhs
Number
of input mxArray
s
prhs
Array of pointers to the
input mxArray
s.
Do not modify any prhs
values in your MEX-file.
Changing the data in these read-only mxArray
s can
produce undesired side effects.
Description
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-hand side arguments,
and the d,e,f...
are right-hand side arguments.
The arguments nlhs
and nrhs
contain
the number of left-hand side and right-hand 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 returned left-hand side mxArray
s.
Examples
See t