Re: oct function question

[Anand Patil]

Thanks for your responses, Paul and Søren.

> Not sure I understand your question.  The matrix object owns the
> data and there is no way to create a new matrix object which points
> to existing data.  Two matrix objects can point to the same data,
> but the data is copied if either are modified.


What I'd ultimately like to do is pass an output matrix into an oct 
function, manipulate it as a C array, and have the changes persist when 
the oct function terminates without any data copying at all (data in 
matrices are passed into oct functions by reference, correct?). Here's a 
bare-bones example:

----------------------oct function:--------------------------

DEFUN_DLD(change_matrix, args, , "Changes all the elements of a 2X2 
matrix to 1")
{
   double* A = args(0).matrix_value().<<fortran_vec, data, etc.>>()
   for(int i=0; i<4; i++) A[i] = 1.0;
}

-------------------------Desired functioning in 
Octave:-------------------------------

octave:1> A = zeros(2);
octave:2> change_matrix(A)

A =

   1  1
   1  1

octave:3>
---------------------------------------------------------------------------

Could you recommend a best method for doing that?

Cheers,
Anand