MATLAB: Do I receive the error “Mex file entry point is missing?”

entryfileMATLAB Compilermexmexfunctionmissingpoint

When I try to compile my foo.c, I receive an error like the following:

Mex file entry point is missing. Please check the (case-sensitive)

spelling of mexFunction (for C MEX-files), or the (case-insensitive)

spelling of MEXFUNCTION (for FORTRAN MEX-files).

??? Invalid MEX-file

Best Answer

This error is due to the fact that "mexFunction" or the parameters may be incorrect. Make sure you have:

void mexFunction( int nlhs, mxArray *plhs[], int nrhs, const mxArray *prhs[] )

In order to have a valid mex source code, the above function needs to replace "main()" with "void mexFunction( int nlhs, mxArray *plhs[], int nrhs, const mxArray *prhs[] )"

For more information, see:

https://www.mathworks.com/help/releases/R13sp2/techdoc/matlab_external/ch03crea.html#calling_from_matlab

Under "Examples of C MEX-files".

Related Solutions

MATLAB: C-Mex Error: expected “…” or “,”

mxArray*plhs[] needs a comma after it

MATLAB: Does the advanced C MEX-file example on using LAPACK and BLAS functions fail to compile and build correctly

This enhancement has been incorporated in Release 2007b (R2007b). For previous product releases, read below for any possible workarounds:

This error occurs because no prototype for dgemm exists in the sample code or in mex.h. Furthermore, when building the MEX-file, you need to link against the import library for the BLAS library, "libmwlapack.lib".

The code below is the modified version of the code that includes the prototype of the dgemm routine (The prototypes for other BAS and LAPACK routines can be found in blas.h and lapack.h, respectively, in the $matlabroot\extern\include folder, where $matlabroot is the MATLAB installation directory, obtained by typing 'matlabroot' at the MATLAB command prompt):

 #include "mex.h"
 /* Prototype for the DGEMM routine */
 extern void dgemm(char*, char*, int*, int*, int*, double*, 
                   double*, int*, double*, int*, double*, double*, int*);
 void mexFunction(int nlhs, mxArray *plhs[], int nrhs, const mxArray *prhs[])
 {
   double *A, *B, *C, one = 1.0, zero = 0.0;
   int m,n,p;
   char *chn = "N";
   A = mxGetPr(prhs[0]);
   B = mxGetPr(prhs[1]);
   m = mxGetM(prhs[0]);
   p = mxGetN(prhs[0]);
   n = mxGetN(prhs[1]);
   if (p != mxGetM(prhs[1])) {
     mexErrMsgTxt("Inner dimensions of matrix multiply do not match");
   }
   plhs[0] = mxCreateDoubleMatrix(m, n, mxREAL);
   C = mxGetPr(plhs[0]);
   /* Pass all arguments to Fortran by reference */
   dgemm (chn, chn, &m, &n, &p, &one, A, &m, B, &p, &zero, C, &m);
 }

To compile the code with LCC, first run:

mex -setup

and choose the LCC compiler. The command to compile the MEX-file is:

mex dgem2.c D:\Applications\MATLAB701\extern\lib\win32\lcc\libmwlapack.lib

where $MATLAB is the root MATLAB directory. To run the MEX-file, execute:

A = magic(10);
B = rand(10);
out = mex_dgemm(A,B);

Best Answer

Related Solutions

MATLAB: C-Mex Error: expected “…” or “,”

MATLAB: Does the advanced C MEX-file example on using LAPACK and BLAS functions fail to compile and build correctly

Related Question