Pfthb

This is the problem:

I have a C code that creates an array nRows x 2, called InitialArray filled with random numbers. Then I split that array into two parts, that is the first column is called xProcess and the second column of the array is yProcess.
The goal is to pass these variables I created (xProcess and yProcess) to Matlab and there a Matlab function based on probabilities rules will put NaN in some of the elements of xProcess and yProcess, and will fill empty arrays called xC and yC with the values of xProcess and yProcess before turning to NaN.
Finally, the C code gets all four arrays back again, perform some operations on them and send them again to Matlab. This process is repeated for a number of time steps.

Here is a piece of the code:

int main ( void )

Engine *ep;
if (!(ep = engOpen(""))) 

 fprintf(stderr, "nCan't start MATLAB enginen");
 return EXIT_FAILURE;


mxArray *xProcess = NULL;
mxArray *yProcess = NULL; 
mxArray *xC = NULL;
mxArray *yC = NULL;

int timeStep;
int numberProcess = 4e6;
int numberC = 0;

So far I created the mxArray, and the number of random numbers that will be stored in xProcess and yProcess. Now comes the loop.

for (timeStep=0 ; timeStep<numberTimeSteps ; timeStep++)

double *arrayTempxProcess;
arrayTempxProcess = (double *)calloc(numberProcess, sizeof(double)); 
double *arrayTempyProcess;
arrayTempyProcess = (double *)calloc(numberProcess, sizeof(double)); 

double *arrayTempxC;
arrayTempxC=(double *)calloc(numberC, sizeof(double)); 
double *arrayTempyC;
arrayTempyC=(double *)calloc(numberC, sizeof(double)); 

xProcess = mxCreateDoubleMatrix(numberProcess, 1, mxREAL); 
yProcess = mxCreateDoubleMatrix(numberProcess, 1, mxREAL);

xC = mxCreateDoubleMatrix(numberC, 1, mxREAL); 
yC = mxCreateDoubleMatrix(numberC, 1, mxREAL);

memcpy((void *)mxGetPr(yProcess), (void *)arrayTempyProcess, numberProcess*sizeof(double));
memcpy((void *)mxGetPr(xProcess), (void *)arrayTempxProcess, numberProcess*sizeof(double));

As you see xC and yC I create them as empty. I believe this is equivalent to xC = and yC = in Matlab. And the arrayTempyProcess and arrayTempxProcess are temporal arrays that each of them gets a column of InitialArray.

if(timeStep>0)
memcpy((void *)mxGetPr(yC), (void *)arrayTempyC,(numberC)*sizeof(double));
memcpy((void *)mxGetPr(xC), (void *)arrayTempxC, (numberC)*sizeof(double)); 

Now I send them to Matlab

engPutVariable(ep, "xProcess", xProcess);
engPutVariable(ep, "yProcess", yProcess);
engPutVariable(ep, "xC", xC);
engPutVariable(ep, "yC", yC);


free(arrayTempxProcess);
free(arrayTempyProcess);
free(arrayTempxC);
free(arrayTempyC);

Now the Matlab function puts NaN in xProcess and yProcess, and fills xC and yC.

printf("Entering MATLAB n");
engEvalString(ep, "[xProcess,yProcess,xC, yC] = my_matlab_function(xProcess,yProcess,xC, yC);"); 
printf("Leaving MATLAB n");

Now comes trouble... Now I am trying to get the results... but the function mxGetM(xC) produces a segmentation fault in the first time step that I don't understand.

xC = engGetVariable(ep,"xC"); 
int mRowsC = mxGetM(xC);


double *XC = NULL;
XC = (double *)malloc (mRowsC*sizeof(double) );
memcpy(XC, mxGetData(xC),mRowsC*sizeof(double));


yC = engGetVariable(ep,"yC");
double *YC = NULL;
YC = (double *)malloc (mmy*sizeof(double) );
memcpy(YC, mxGetData(yC),mmy*sizeof(double));


xProcess = engGetVariable(ep,"xProcess"); 
int mRowsProcess = mxGetM(xProcess);


double *XPROCESS = NULL;
XPROCESS = (double *)malloc (mRowsProcess*sizeof(double) );
memcpy(XPROCESS, mxGetData(xPROCESS),mRowsProcess*sizeof(double));


yProcess = engGetVariable(ep,"yProcess");

double *YPROCESS = NULL;
PROCESS = (double *)malloc (mRowsProcess*sizeof(double) );
memcpy(YPROCESS, mxGetData(yProcess),mRowsProcess*sizeof(double));



numberC = mRowsC;

mxDestroyArray(xProcess);
mxDestroyArray(yProcess);
mxDestroyArray(xC);
mxDestroyArray(yC);
free(XPROCESS);
free(YPROCESS);
free(XC);
free(YC);

I have tried to reduce the number of elements in xProcess and yProcess but I get the segmentation fault at some point later than the first time step.
The weird thing about this, is that I also tried to save the results in Matlab after printf("Leaving MATLAB n"); but it didn't work out. It saved nothing.

I'm new coupling C and Matlab, so my code might be entirely wrong, but is there any limits in which C cannot be coupled with Matlab functions?

Any help is appreciated. Thanks!