MATLAB: Mex: out of memory mxCreateNumericArray

arraycdimdimensionlarge arrayMATLABmemorymexmxcreatenumericarrayout of memory

Hello,

i m getting an error "out of memory" when i m declaring an large array. but when i m declaring an small array it works. Unfortunately i m beginner in mex. Can someone tell pls how i can solve this problem? Many many thanks!

// works
int dim[3] = {400,3,1000};
plhs[0] = mxCreateNumericArray(3, dim, mxDOUBLE_CLASS, mxREAL);
// doesnt work
int dim[3] = {4000,3,10000};
plhs[0] = mxCreateNumericArray(3, dim, mxDOUBLE_CLASS, mxREAL);

Best Answer

Hi,

that works fine for me. I assume you use a 32bit MATLAB? The variable you create needs 960mb of memory in one piece which is most likely not available for you.

You can use the memory command (Windows only!) to see what the biggest matrix is you can allocate.

Small advice: Don't use an int for the dimensions. Use mwSize. This is a bittedness independent type.

Related Solutions

MATLAB: Incompatible type with mxCreateNumericArray

It is complaining because you declared outDims as an int array (which when used as an argument gets converted to const int *), but the function expected something else (const size_t *). Use an mwSize for this to be generic. Try this:

void mexFunction(int nlhs, mxArray *plhs[], int nrhs, const mxArray *prhs[])
{
    :
const mwSize outDims[4] = {nS,Y_dimx,Y_dimy,Y_dimz};

MATLAB: How to use mxCreateNumericArray

This line is incorrect (wrong function and signature):

plhs[0]    = mxCreateNumericArray(xynum,1,mxINT16_CLASS); /*Creates a matrix*/

It should be this instead:

plhs[0]    = mxCreateNumericMatrix(xynum,1,mxINT16_CLASS,mxREAL); /*Creates a matrix*/

Also, these lines will not work:

    int gnum, xynum, *gn;
        :
    gn         = mxGetInt16s(plhs[0]);                        /*Set to be the first of the output values*/

An int on your system is almost surely a 32-bit integer, not a 16-bit integer. You need to make sure your pointer definition matches exactly what is in memory. E.g., you can probably use a short int for this:

    int gnum, xynum;
    short *gn;
        :
    gn         = mxGetInt16s(plhs[0]);                        /*Set to be the first of the output values*/

That will mean you need to change this signature:

    void findnegs(double *phi, int gnum, int xynum, int *gn, double *adj, double *newphi, double *dphidtSum)

to this instead also:

    void findnegs(double *phi, int gnum, int xynum, short *gn, double *adj, double *newphi, double *dphidtSum)

But this begs the question, are integer calculations in the findnegs function now going to overflow your 16-bit integers in gn? You may need to adjust your code to make sure this isn't a problem.

Best Answer

Related Solutions

MATLAB: Incompatible type with mxCreateNumericArray

MATLAB: How to use mxCreateNumericArray

Related Question