Re: Casting a Matrix object as a single dimensional array

[David Grundberg]

On 06/08/2010 02:16 PM, Chidambaram Annamalai wrote:
> I still don't see how I can access the internal double* pointer. Could
> you please elaborate? (That is, show a simple example?)
>
> Thanks,
> Chillu
>
> On 6/7/10, David Grundberg<address@hidden>  wrote:
> > On 06/07/2010 12:54 PM, Chidambaram Annamalai wrote:
> > > I am writing C++ code to manipulate Matrix objects using the octave
> > > headers. I want to copy it to the GPU, for which I require a pointer
> > > to the underlying chunk of memory the Matrix object stores its data
> > > in. Is there a way to do this?
> > >
> > > If I cannot get the pointer (due to private visibility mode etc. or
> > > otherwise) what's the most efficient (in terms of least amount of
> > > memory copies) way to do this?
> > >
> > > I hope there's a better way than creating my own vanilla array and
> > > copying the elements of the matrix because the matrices are very large
> > > in size.
> > >
> > > Thanks,
> > > Chillu
> >
> > These functions are part of the Array<T>  class:
> >
> > const T * data  (void) const
> > const T * fortran_vec (void) const
> > T * fortran_vec (void)
> >
> > And Matrix inherits from Array<double>  (via MArray<double>).
> >
> > David

Please reply on the bottom of the post. It makes the thread easier to 
follow.

    Matrix mymatrix (4, 4);
    double * ptr;

    ptr = mymatrix.fortran_vec ();

    for (int i = 0; i < 16; i++)
        ptr[i] = i;

    const double * cptr;

    cptr = mymatrix.fortran_vec (); // or data ()

    for (int i = 0; i < 16; i++)
        printf ("%1.0f, ", cptr[i]);

David