Octave equivalent to A = mxGetPr(prhs[0]);

[Fredrik Lingvall]

Hi all,

I want to get a pointer to an input parameter (a large matrix) in an octave
DLD-function (oct file) without making a copy of the input data. In a 
Matlab
mex-file I would do,

A_M = mxGetM(prhs[0]);
A_N = mxGetN(prhs[0]);
A = mxGetPr(prhs[0]);

to get the matrix size and a pointer to the data.  For octave, I have tried

A_M = args(0).matrix_value().rows();
A_N = args(0).matrix_value().cols();
A = args(0).matrix_value().fortran_vec();

A_M and A_N get the correct values but the pointer A do not seem to 
point to the data.
What am I doing wrong here?

/Fredrik