Using the C++ Math Library

GetData( )

The most basic of the functions is GetData(), which returns a pointer to the array data structure. This pointer is of type mxArray*. The array structure is an opaque data type, one in which the field names are unknown to the user. Access functions allow you to read and write the fields of the structure.

For example, to retrieve a pointer to the C++ array of double precision floating point numbers stored in an mxArray *, call mxGetPr() (to retrieve the real part of the array) or mxGetPi() (to retrieve the complex part). You can combine these calls with calls to GetData():

mwArray A = magic(17);
double *real_data = mxGetPr(A.GetData());

Note    Be careful with the pointers that GetData(), mxGetPr(), and mxGetPi() return. You must never free them or assign to them because the functions return pointers to the real data stored in the mwArray. Freeing them will cause a memory error later on.

For more details on the mxArray type, see the MATLAB Application Program Interface Guide or the header file <matlab>/extern/include/matrix.h. Accessing Online Reference Documentation describes how to access the Help Desk.

Extracting Data from an mwArray

SetData( )