Accessing matrices stored inside of cell arrays using MEX files in MATLAB
Date: 2022-11-23 14:59:10
I am currently writing a MEX function that will have to work with a cell array in MATLAB. The MEX file is written in C.
Essentially, the input to my function will be a cell array where each entry is a numeric matrix with real values. A simple example is:
C = cell(1,2);
C{1} = ones(10,10);
C{2} = zeros(10,4);
I would like to be able to access the numeric arrays C{1} and C{2} in my MEX file. Ideally, I would like to do this without having to create a second copy of the data in my MEX File (i.e. get pointers for them).
Using the previous example, my current approach is as follows:
/* declare a pointer variable to the incoming cell array after it is passed to the MEX function */
mxArray C_CELL = (mxArray *) mxGetData(prhs[0])
/* declare a 2 x 1 array of pointers to access the cell array in C */
double *myarray[2] //
/* point towards the contents of C_CELL */
myarray[0] = mxGetPr(C_CELL[0])
myarray[1] = mxGetPr(C_CELL[1])
Unfortunately this seems to yield "invalid use of undefined type 'struct mxArray_tag'" errors.