'delauney3' fails

[Søren Hauberg]

Hi All

I've tried the following example from the Mathworks webpage [1]

d = [-1 1];
[x,y,z] = meshgrid(d,d,d); % A cube
x = [x(:);0];
y = [y(:);0];
z = [z(:);0];
% [x,y,z] are corners of a cube plus the center.
Tes = delaunay3(x,y,z)

and it fails for me with the following error:

qhull internal error (qh_qhull): temporary sets not empty (2)

While executing: | qhull d Qt Qbb Qc
Options selected for Qhull 2003.1 2003/12/30:
delaunay Qtriangulate Qbbound-last Qcoplanar-keep _pre-merge
_zero-centrum Pgood Qinterior-keep _max-width 2 Error-roundoff 4e-15
_one-merge 3.6e-14 Visible-distance 2.4e-14 U-coplanar-distance 2.4e-14
Width-outside 4.8e-14 _wide-facet 1.5e-13
Last point added to hull was p5. Last merge was #10.

At error exit:

Delaunay triangulation by the convex hull of 9 points in 4-d:

Number of input sites: 9
Number of Delaunay regions: 0
Number of non-simplicial Delaunay regions: 7

Statistics for: | qhull d Qt Qbb Qc

Number of points processed: 9
Number of hyperplanes created: 12
Number of facets in hull: 7
Number of distance tests for qhull: 45
Number of distance tests for merging: 147
Number of distance tests for checking: 72
Number of merged facets: 10

error: __delaunayn__: qhull failed.
error: called from:
error: /home/sh/Dokumenter/octave/octave-hg/upstream/scripts/geometry/delaunayn.m at line 55, column 5
error: /home/sh/Dokumenter/octave/octave-hg/upstream/scripts/geometry/delaunay3.m at line 43, column 12


Søren

[1] http://www.mathworks.com/access/helpdesk/help/techdoc/index.html?/access/helpdesk/help/techdoc/ref/delaunay3.html

[Jaroslav Hajek]

Post by Søren Hauberg
Hi All
I've tried the following example from the Mathworks webpage [1]
       d = [-1 1];
       [x,y,z] = meshgrid(d,d,d);  % A cube
       x = [x(:);0];
       y = [y(:);0];
       z = [z(:);0];
       % [x,y,z] are corners of a cube plus the center.
       Tes = delaunay3(x,y,z)

Works for me, apparently:
Tes =

4 9 3 1
4 9 2 1
7 9 3 1
7 9 5 1
7 4 9 3
7 4 8 9
6 9 2 1
6 9 5 1
6 4 9 2
6 4 8 9
6 7 9 5
6 7 8 9

IIRC, miscompiled qhull is not uncommon (it's sensitive to flags), so
maybe that's the source of your problem.

cheers