[OctDev] griddata / delaunay

[Jonathan S. <jjs...@sb...>]

I have encountered a problem with griddata when using semi-regular input 
points.  The issue has to do with facet merging when running delaunay, 
via qhull, with defualt options.  To avoid this, delaunay should be run 
with the "QJ" option.  Perhaps this should be mentioned explicitly in 
the delaunay help.  For the worst case of a rectangular grid, a 
segmentation fault occcurs:

octave:1> [x,y]=meshgrid(1:10,1:10);
octave:2> delaunay(x(:),y(:),"QJ")
(plot of triangles)
octave:3> delaunay(x(:),y(:))
panic: Segmentation fault -- stopping myself...
attempting to save variables to `octave-core'...
save to `octave-core' complete
Segmentation fault

Attached is a patch for griddata which calls delaunay with the "QJ" option.

Regards,
Jonathan