slice implementation

[John W. Eaton]

On 23-Nov-2007, Kai Habel wrote:

| I have implemented the slice function, which is useful to visualize 3D
| scalar fields by means of slices. Since we have some pending patches for
| __go_draw_axes__, ... (and I have some applied locally) I am not sure if
| slice works without warnings or errors using the current cvs. If series
| of patches from David is applied, I will look at slice again and see if
| some modifications are needed.
| 
| I think slice shows a further problem with gnuplot, If you take the
| example code and try to plot three orthogonal slices
| slice(X,Y,Z,V,0,0,0) instead of slice(X,Y,Z,V,[],0,[]) you see a
| distorted plot, because the depth ordering does not work for this case.
| Maybe you have an idea?

I added this function.  I'm seeing

  octave:5> slice (x, y, z, v, xi, yi, zi);
  error: surface::defaults: not implemented
  error: called from `surface' in file 
`/home/jwe/src/octave-trunk/scripts/plot/surface.m'
  error: evaluating assignment expression near line 163, column 17
  error: evaluating if command near line 130, column 3
  error: called from `slice' in file 
`/home/jwe/src/octave-trunk/scripts/plot/slice.m'
           line 1059: undefined variable: Inf

Is there some pending patch that is required to make this work?

Thanks,

jwe