Undefined reference to mexPrintf for simple helloworld program

I've been trying to get started using mex to compile c code for use in simulink s functions. The code below throws an undefined reference error upon compiling.

#include "mex.h"
#include <math.h>
#include <matrix.h>

void mexFunction(int nlhs, mxArray *plhs[], int nrhs, const mxArray *prhs[])
{
  mexPrintf("Hello World!\n");
}

undefined reference to `mexPrintf'
collect2.exe: error: ld returned 1 exit status

mex -setup displays

MEX configured to use 'MinGW64 Compiler (C)' for C language compilation.
Warning: The MATLAB C and Fortran API has changed to support MATLAB
   variables with more than 2^32-1 elements. In the near future
   you will be required to update your code to utilize the
   new API. You can find more information about this at:
   http://www.mathworks.com/help/matlab/matlab_external/upgrading-mex-files-to-use-64-bit-api.html.

To choose a different language, select one from the following:
 mex -setup C++ 
 mex -setup FORTRAN

Please let me know if you see the issue.

Answer 1

[James Tursa]

Your code is a standard mex routine that can be compiled and run at the MATLAB command line prompt as follows:

mex helloworld.c % or whatever the actual filename is
helloworld

s-function mex code has a different interface from what is in your code above that involves input & output ports etc. Maybe you could start with the s-function mex examples in the doc and then adapt it to what you need.

[Mitchell Hoffmann]

Yes that is how I've been compiling it. The s function builder and s function examples all fail to compile as well (undefined reference to mxCalloc among other errors). I expect this error is related to the other one and was trying to solve it in the simpler case first.

Maybe another good thing to note is that if I replace

#include "mex.h"

with

include <stdio.h>

and mexPrintf with printf, it compiles but then gives this error on execution.

Invalid MEX-file 'R:\path\helloworld.mexw64':
R:\path\helloworld.mexw64 is not a valid Win32
application.

I am running 64 bit matlab on a 64 bit machine so this error is also perplexing.