2-D cell array
Pointer to the created mxArray, if successful. If unsuccessful in a standalone (non-MEX-file) application, returns NULL in C (0 in Fortran). If unsuccessful in a MEX-file, the MEX-file terminates and returns control to the MATLAB® prompt. The function is unsuccessful when there is not enough free heap space to create the mxArray.
Use mxCreateCellMatrix to create an m-by-n two-dimensional cell mxArray. The created cell mxArray is unpopulated; mxCreateCellMatrix initializes each cell to NULL in C (0 in Fortran). To put data into cells, call mxSetCell.
mxCreateCellMatrix is identical to mxCreateCellArray except that mxCreateCellMatrix can create two-dimensional mxArrays only, but mxCreateCellArray can create mxArrays having any number of dimensions greater than 1.
See the following examples in matlabroot/extern/examples/mx.