contour produces an empty figure

[Richard Bovey]

contour() unexpectedly produces an empty figure.

I used the example from the help text, an example session is given below. This results in an empty figure.

I'm using octave version 3.0.1 with Graphics backend: jhandles on Windows XP.

Regards,
Richard

---------

>> OCTAVE_VERSION
ans = 3.0.1
>> help contour
 -- Function File:  contour (Z)
 -- Function File:  contour (Z, VN)
 -- Function File:  contour (X, Y, Z)
 -- Function File:  contour (X, Y, Z, VN)
 -- Function File:  contour (..., STYLE)
 -- Function File:  contour (H, ...)
 -- Function File: [C, H] = contour (...)
     Plot level curves (contour lines) of the matrix Z, using the
     contour matrix C computed by `contourc' from the same arguments;
     see the latter for their interpretation.  The set of contour
     levels, C, is only returned if requested.  For example:

          x = 0:2;
          y = x;
          z = x' * y;
          contour (x, y, z, 2:3)

     The style to use for the plot can be defined with a line style
     STYLE in a similar manner to the line styles used with the `plot
     command.  Any markers defined by STYLE are ignored.

     The optional input and output argument H allows an axis handle t
     be passed to `contour' and the handles to the contour objects to
     returned.

     See also: contourc, patch, plot.

D:\Applications\Octave\share\octave\3.0.1\m\plot\contour.m

Additional help for built-in functions and operators is
available in the on-line version of the manual.  Use the command
`doc <topic>' to search the manual index.

Help and information about Octave is also available on the WWW
at http://www.octave.org and via the [e-mail]
mailing list.
>> x = 0:2;
>> y = x;
>> z = x' * y;
>> contour (x, y, z, 2:3)
>>