Re: oct files

[Paul Kienzle]

branganj wrote:

> Hi, 
> I have tried to dynamically link a function, but I get the following warnings:
>
> With mkoctfile mpi_mm.cc  I get:
>
> mpi_mm.cc: In function `class octave_value_list Fmpi_mm(const class 
> octave_value_list &, int)':
> mpi_mm.cc:35: warning: unused variable `int nbytes'
> mpi_mm.cc:133: warning: control reaches end of non-void function 
> `Fmpi_mm(const octave_value_list &, int)'
You are not returning an octave_value_list() from your function.  The
usual style is:

   octave_value_list retval;

   if (some error) {
      error("message");
   } else {
      retval(0) = returned_value;
   }
   return retval;

> There is an oct file created, but in octave when I call the function it gives 
> :
>
> error: Segmentation fault -- stopping myself...
> attempting to save variables to `octave-core'...
> save to `octave-core' complete
>
> Segmentation fault (core dumped)
>
>
> I have defined the function with DEFUN_DLD (mpi_mm, , ,"Parallel 
> multiplication of two matrices using mpi")
>
> And execution is throug mpi_mm(0,0)
>
> So I shouldn't be passing in any octave_value_lists??Or is it ok to leave it 
> blank??
> Do I need to have a return value? Can this be an octave_matrix ? At the moment 
> I have it only printing out stuff, but I have tried with another type 
> returning an octave_matrix, but this doesn't get a .oct file created.
See above.  The return value can be any octave_value_list.  It's not
surprising it doesn't work with no return value.  To return a matrix,
do the following:

   Matrix r(n,m);
   ...
   retval(0) = r;
   return retval;

Da Coda Al Fine [http://octave.sf.net/coda/coda.html] talks
about this sort of thing.

Paul Kienzle
address@hidden



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