MATLAB: Mex file crash after many run

crashiterationMATLABmemorymex

Hi,
I have a mex function which I am using in a loop. After many iterations matlab gives access violation error and crashes. When I did a little search I found out that it may be resulting from memory allocation. Is there any way to define inputs and outputs differently that I will not get this crash problem? Or should I search for the solution somewhere else in the c code?
Thank you.
Ezgi Köker
void mexFunction(int nlhs, mxArray *plhs[], int nrhs,
                 const mxArray *prhs[])
{
double *altsin,  *ustsin,  
       *altkis,  *ustkis,
       *xx,     *xi,   *fonk,
       *afr, *mrg, *y, *x, *qs, lo;
long   *ndeg, *lver,
      *gedeg, edeg, ferti, kac,
       nx, ny, nyi, amac;
int a, b;
int sonuc;                  
int carpan=0,i;
/* Defining inputs */
nx = mxGetScalar(prhs[0]);     
ny = mxGetScalar(prhs[1]);      
nyi = mxGetScalar(prhs[2]);      
amac = mxGetScalar(prhs[3]);     
ndeg = mxGetData(prhs[4]);            
altsin = mxGetPr(prhs[5]);            
ustsin = mxGetPr(prhs[6]);            
altkis = mxGetPr(prhs[7]);           
ustkis = mxGetPr(prhs[8]);            
xi = mxGetPr(prhs[9]);               
lo = mxGetScalar(prhs[10]);     
a = (int)nvars_in+1;
b = (int)nfun_in+1;
   /* Defining outputs */
  plhs[0] = mxCreateDoubleMatrix(1,a, mxREAL);
  xx = mxGetPr(plhs[0]);                           
plhs[1] = mxCreateDoubleMatrix(1,b, mxREAL);
fonk = mxGetPr(plhs[1]);                         
plhs[2] = mxCreateDoubleMatrix(1,b, mxREAL);
afr = mxGetPr(plhs[2]);                       
plhs[3] = mxCreateDoubleMatrix(1,b, mxREAL);
mrg = mxGetPr(plhs[3]);                        
plhs[4] = mxCreateNumericMatrix(1,a, mxUINT32_CLASS, mxREAL);
lver = mxGetData(plhs[4]);                    
plhs[5] =mxCreateNumericMatrix(1,b, mxUINT32_CLASS, mxREAL);
gedeg = mxGetData(plhs[5]);                     
plhs[6] =mxCreateDoubleMatrix(1,1, mxREAL);       
qs = mxGetPr(plhs[6]);                          
      sevket( nx,  ny,  nyi,  amac,
             ndeg, altsin,  ustsin,  altkis,  ustkis,
             xx,  xi, fonk,  mrg,  lver,
             redgr,  gedeg,  edeg, ferti, kac,
             carpan,  sonuc, sonuc, a, b, qs, lo);
}

Best Answer

Do not use a long to catch the output of mxGetScalar, which replies a double. int is not a good choice also for a and b, when the documentation explains clearly, that mxCreateDoubleMatrix expects an mwSize.
It is much safer to specify the wanted data type directly using int64_T or mwSize, size_t etc. Letting the compiler decide which data type to use4, is a fragile method. E.g.:
long *ndeg
ndeg = mxGetData(prhs[4]);
If prhs[4] is a int32, use:
int32_T *ndeg
if (!mxIsInt32(prhs[4])) {
   mexErrMsgIdAndTxt("YourFunc:BadInput:In5", "5th input must be an INT32");
}
ndeg = (int32_T *) mxGetData(prhs[4]);
But I guess boldly, that the problem is hidden inside sevget. Perhaps you access unallocated memory. Start with cleaning the types and then test the code again exhaustively.
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