Re: How to use "do_colon_op" in an oct-file?

[Lukas Reichlin]

On 15.10.2015, at 17:06, "John W. Eaton" <address@hidden> wrote:

> On 10/15/2015 10:55 AM, Lukas Reichlin wrote:
>> Dear Octave Community
>> 
>> I'm writing an oct-file [1] for the control package where I want to use the 
>> colon operator:
>> 
>>      octave_value mat_idx = do_colon_op (1, idx);
>> 
>> However, I get the following compiler error:
>> 
>> __lti_input_idx__.cc:50:28: error: use of undeclared identifier 'do_colon_op'
>>    octave_value mat_idx = do_colon_op (1, idx);
>>                           ^
>> 
>> How can I fix this error? Thanks in advance for every help!
> 
> What are you trying to do?
> 
> jwe
> 
> 

I'm trying to substitute the following function with C++ using DEFUN_DLD:

function [mat_idx, opt_idx] = __lti_input_idx__ (varargin)

  str_idx = find (cellfun (@ischar, varargin));

  if (isempty (str_idx))
    mat_idx = 1 : nargin;
    opt_idx = [];
  else
    mat_idx = 1 : str_idx(1)-1;
    opt_idx = str_idx(1) : nargin;
  endif

endfunction

In the file  libinterp/corefcn/data.cc,  I found the expression

        retval = do_colon_op (args(0), args(1));

on line 6322 (inside definition of DEFUN (colon, args, …) on lines 6305-6335) 
and tried to use it in my C++ code.

Lukas