MATLAB: Could you please compile this as mex for windows 64 bit ? I can not run the compiler. Faster exp function with reduced accuracy.

Question

Code for Exp function with reduced accuracy. I can not compile it.

Code from

https://www.mathworks.com/matlabcentral/newsreader/view_thread/173567

http://www-h.eng.cam.ac.uk/help/tpl/programs/Matlab/mex.html

#include <stddef.h>
#include <math.h>
#include "mex.h"
#ifndef mwSize
#define mwSize int
#endif
/* these 2 #define lines help make the later code more
readable */
/* Input Arguments */
#define PARAMETER_IN prhs[0]
/* Output Arguments */
#define RESULT_OUT plhs[0]
#define LITTLE_ENDIAN 1
static union
{
  double d;
  struct {
#ifdef LITTLE_ENDIAN
    int j,i;
#else
    int i,j;
#endif
  } n;
} _eco;
#define EXP_A (1048576/0.69314718055994530942)
#define EXP_C 60801
#define EXP(y) (_eco.n.i = EXP_A*(y) + (1072693248 - EXP_C), _eco.d)
void mexexp(double*y, double*yp, mwSize m) {
  while(m--) {
    *yp++ = EXP(*y++);
  }
}
void mexFunction( int nlhs, mxArray *plhs[],
                  int nrhs, const mxArray*prhs[] )
{
    mwSize numel;
    mwSize ndim;
    mwSize *dims;
        /* Check for proper number of arguments */
        if (nrhs != 1) {
            mexErrMsgTxt("One input argument required.");
        } else if (nlhs > 1) {
            mexErrMsgTxt("Too many output arguments.");
        } else if ( !mxIsDouble(PARAMETER_IN) ) {
            mexErrMsgTxt("Input must be double.");
        } else if ( mxIsComplex(PARAMETER_IN) ) {
            mexErrMsgTxt("Input cannot be complex.");
        }
        ndim = mxGetNumberOfDimensions(PARAMETER_IN);
        dims = mxGetDimensions(PARAMETER_IN);
        numel = mxGetNumberOfElements(PARAMETER_IN);
        /* Create a matrix for the return argument */
        RESULT_OUT = mxCreateNumericArray(ndim, dims,
    mxDOUBLE_CLASS, mxREAL);
        /* Do the actual computation*/
        mexexp(mxGetPr(PARAMETER_IN),mxGetPr(RESULT_OUT),numel);
        return;
    }

Answer 1

Here is a compiled version: RoughExp.mex

You might need the MSVC 2010 runtime libs, if you did not install them before: http://www.microsoft.com/en-us/download/details.aspx?id=14632