Why does LIBFUNCTIONS not display more than 8 return arguments in MATLAB 7.6 (R2008a)?

I have the following two function declarations in my header file:

// 8 pointer argument function

__declspec(dllexport)double myfun8(double *a, double *b, double *c, double *d, double *e, double *f, double *g,double* h);

//9 pointer argument function

__declspec(dllexport)double myfun9(double *a, double *b, double *c, double *d, double *e, double *f, double *g, double * h, double *i);

I create a DLL using Visual C++ 2005 express edition and load it into MATLAB using the LOADLIBRARY function. However, when I inspect the imported function using the function: LIBFUNCTIONS, the function signatures are not consistent:

 [ doublePtr, doublePtr, doublePtr, doublePtr, doublePtr, doublePtr, doublePtr, doublePtr] myfun8(doublePtr, doublePtr, doublePtr, doublePtr, doublePtr, doublePtr, doublePtr, doublePtr)

 double myfun9(doublePtr, doublePtr, doublePtr, doublePtr, doublePtr, doublePtr, doublePtr, doublePtr, doublePtr)

The function with 9 output arguments is shown to have only one output argument.

Answer 1

[MathWorks Support Team]

This is a limitation of the METHODS, METHODSVIEW, LIBFUNCTIONS, and LIBFUNCTIONVIEW functions in MATLAB release version up to and including MATLAB 7.6 (R2008a). METHODS -full does not list more then 8 output arguments and displays only the first output. Note that the function can still be called correctly and all outputs are returned.

A workaround to view the full function signature is to use the following:

libpkg=findpackage('lib'); 

class=findclass(libpkg,'fifteenArgDLL'); 

methods=class.methods;

The "method" variable would then contain information about the library:

%Sample invocation:

>> get(methods(1))

                  Name: 'myfun'

           Description: 'myfun'

             Signature: [1x1 schema.signature]

                Static: 'on'

      FirstArgDispatch: 'on'

>> get(methods(1).Signature)

       InputTypes: {16x1 cell}

      OutputTypes: {17x1 cell}

        Varargout: 'off'

         Varargin: 'off'

>> methods(1).Signature.OutputTypes

ans = 

      'double'

      'doublePtr'

      'doublePtr'

      'doublePtr'

      'doublePtr'

      'doublePtr'

      'doublePtr'

      'doublePtr'

      'doublePtr'

      'doublePtr'

      'doublePtr'

      'doublePtr'

      'doublePtr'

      'doublePtr'

      'doublePtr'

      'doublePtr'

      'doublePtr'