Re: Memory management in .oct files

[Richard Hindmarsh]

> |   int ir = xin1.rows();                                    // #3
> |   int ic = xin1.cols();
> |   Matrix xout1(ic,ir);                                     // #4
> |   for (int ir1 = 0 ; ir1 < ir ; ir1++)                     // #5
> |     for (int ic1 = 0 ; ic1 < ic ; ic1++) {
> |       xout1(ic1,ir1) = xin1(ir1,ic1);                      // #6
>
>                         ^^^^^^^^^^^^^
> Since Octave does not know that this indexing operation appears on the
> RHS of the assignment (I think it would be a real mess to try to do
> that automatically), it splits off a copy here.  If you don't plan on
> modifying the argument that is pass to this function, then you can
> avoid the extra copy and the checks on the reference count that are
> done each time you use the indexing operator by declaring xin1 as
> "const".
>
>  
I guess this means that you decided not to impelemt e.g.

    xout1(ic1,ir1) = xin1(ir1,ic1); 

using a helper class. The upside of this is speed; the downside is that 
statements such as

     double y = xin1(ir+1,ic+1);

do not trip an error and statements like

    xout1(ir+1,ic+1) = 1;

do not resize the matrix, as they do in Octave. Are there function calls e.g.

    double y = xout1.rhsindexing(ir+1,ic+1);
    xout1.lhsindexing(ir+1,ic+1) = 0;

which have the desired behaviour? Is there another route to finding this 
out other than doxygen?

Thanks
Richard



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