delaunayn.m function does not work?

[david]

Hi,

  I tried to use the delaunayn.m function as follows:

Octave:6> X = [-0.5 -0.5  -0.5;-0.5 -0.5   0.5;-0.5  0.5  -0.5;-0.5  0.5   
0.5;0.5 -0.5 -0.5;0.5 -0.5   0.5;0.5  0.5  -0.5;0.5  0.5   0.5];

Octave:7> T = delaunayn(X,{'Qt','Qbb','Qc','Qz'});

error: __delaunayn__: not available in this version of Octave
error: evaluating assignment expression near line 55, column 5
error: called from `delaunayn' in file 
`/usr/local/share/octave/3.0.5/m/geometry/delaunayn.m'

When I see the source code 
/usr/local/share/octave/3.0.5/m/geometry/delaunayn.m

It tried to do this:
t = __delaunayn__ (x, varargin{:});

But I did not find any function named __delaunayn__.m, what is the problem with 
the delaunayn.m?

Thanks.

David