Re: Sparse functions for octave

[John W. Eaton]

On 15-Nov-1999, A+A Adler <address@hidden> wrote:

| On Sat, 13 Nov 1999, John W. Eaton wrote:
| > | Now, I need to add indexing to sparse matrices, to that you can
| > | do:
| > | x(1:2,1:2) for sparse x.
| > 
| > You need to define a function called do_index_op() with the following
| > signature:
| > 
| >   octave_value do_index_op (const octave_value_list& idx)
| > 
| > For example, look at ov-base-mat.cc.
| 
| Unfortunately, I don't seem to be able to get this to work.
| For example, I added the following code to the public 
|    methods of make_int.cc: 
| 
|       octave_value do_index_op (const octave_value_list& idx) {
|         if (idx.length() == 1)
|           return (double) scalar;
|         else
|           error("idx !=1");
|       } 
| 
| But I still get the following error
|    octave-2.1.19:1> x=make_int(1);
|    installing integer type at type-id = 18
|    octave-2.1.19:2> x(1)
|    error: can't perform indexing operations for integer type

Sorry, it looks like I picked out the wrong do_index_op function.  I
should have said to write a function for your class called do_index_op
with the following signature:

  octave_value_list
  octave_integer::do_index_op (int, const octave_value_list& idx)

Here's an example for the integer class defined in make_int.cc:

  octave_value_list
  octave_integer::do_index_op (int, const octave_value_list& idx)
  {
    octave_value retval;

    if (idx.length () == 1 && idx(0).nint_value () == 1)
      retval = octave_value (new octave_integer (scalar));
    else
      error ("idx != 1");

    return retval;
  }

jwe



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