Programming and Graphics

9.4 Transferring data to theMatlabdomain 295

where the literalmxTYPEcan bemxREALfor an array with real elements

ormxCOMPLEXfor an array with complex elements consisting of a real and

an imaginary part.

• Second, we evaluate themxArrayusing the command:

memcpy(mxGetPr(arrayname), xp, sizeof(x));

wherexpis a pointer to the C++ arrayx.

• Third, we transfer themxArrayinto theMatlab-workspace using an
  engine function:

engPutVariable(ep, "name", arrayname);

whereepis the declared engine session pointer name, andnameis the

name of the array in theMatlabdomain.

The following code contained in the filemtrans.ccdefines a numerical
variable, introduces its pointer, transfers the variable in theMatlabdomain,
and prints the variable:

#include <iostream>

#include "engine.h"

using namespace std;

int main()

{

double a = 5.0;

double * ap = &a;

//--- Start a session:

Engine * lva = engOpen("matlab12 -nojvm -nosplash");

//--- Define a character buffer:

const int BUFSIZE=256;

char buffer[BUFSIZE];

engOutputBuffer(lva, buffer, BUFSIZE);

/*--- Reserve the array ‘‘mxa’’

Copy into memory

Transfer the data */

mxArray * mxa = mxCreateDoubleMatrix(1, 1, mxREAL);

memcpy(mxGetPr(mxa), ap, sizeof(a));

engPutVariable(lva, "b", mxa);