matlab have no response after calling a mex function many times

Question

I'm hoping someone can help me with a problem I'm having with some mex code I've written. After calling the same mex function many times, the matlab will have no response. I post the code here:

void mexFunction(int nlhs, mxArray *plhs[], /* Output variables */
        int nrhs, const mxArray *prhs[]) /* Input variables */
{
    const char *fieldnames[3]; //This will hold field names.
    fieldnames[0] = (char*)mxMalloc(20);
    fieldnames[0] = "mean";

    plhs[0] = mxCreateCellMatrix(11, 1);
    mxArray *cells = plhs[0];

    mxArray *treeNodeMean;
    double *mean;
    for(int i = 0; i < 10; ++i) {
        mxArray* treeNode  = mxCreateStructMatrix(1,1,1,fieldnames);
        mxSetCell(cells, i , treeNode);//set treeNode to tree

        //initialize
        treeNodeMean  = mxCreateDoubleMatrix(2,58, mxREAL);

        //set values
        mean = mxGetPr(treeNodeMean);

        for(int j = 0; j<=(58*2);j++) {
            mean[j] = (double)j;
        }

        //set treeNode
        mxSetFieldByNumber(treeNode,0,0, treeNodeMean);//(pointer,index,fieldNumber,value)
    }
    return;
}

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1. When I call the mex function in the command window as fllow:

---

for i = 1:100

A = createTrees;

end

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Matlab not responding after long runing.

2. If I delete the code:

---

for(int j = 0; j<=(58*2);j++) {
    mean[j] = (double)j;
}

---

from the mex function, the case of “Matlab not responding after long runing.” will disappear. So, How can I solve the "No response" problem. Thanks a lot.

Answer 1

The for loop in question is accessing the array out of bounds. C-style indexing goes from 0 to N-1 instead of 1 to N (as in MATLAB), so your loop termination condition should be j<(58*2) instead of <=.

You may also want to double-check the loop termination condition for your outer loop (over i), because that is only looping over 10 elements despite you allocating memory for 11.