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Re: Problems with ExtendGraphics/Delaunay Triangulation

• To: mathgroup at smc.vnet.net
• Subject: [mg53701] Re: Problems with ExtendGraphics/Delaunay Triangulation
• From: David Bailey <dave at Remove_Thisdbailey.co.uk>
• Date: Mon, 24 Jan 2005 03:37:22 -0500 (EST)
• References: <csioin$nnr$1@smc.vnet.net>
• Sender: owner-wri-mathgroup at wolfram.com

jrome at mail.com wrote:
> Hi,
> 
> I've been having a problem with the Delaunay Triangulation command,
> "Delaunay" in a Mathematica notebook I am using. The problem is, the
> program seems to lock up for certain data sets. Specifically, I have a
> 2D array of about 3000 nodes that locks it up. I did some experiments,
> and found that it worked fine for the first 1550 nodes, but not the
> first 1575 nodes. Upon looking at the data set, I noticed that 4 nodes
> in that range (between 1500 & 1575) were consecutively numbered and in
> a straight line. When I altered this values by less than 1%, the
> Delaunay triangulation worked fine.
> 
> So, I decided to go back to my code (as I was writing this question, as
> a matter of fact!), and added a small random number to every value in
> my matrix. This is not an ideal solution, but it seems to work for now.
> I'd still like to figure out what the problem with the Delaunay
> triangulation is, and find out if there are better solutions to my
> problem. Thank you very much. You've already been a big help!
> 
I think you should also post a simple example to Wolfram support - after 
all, the only way they will get rid of bugs like this is iff people tell 
them about them!

David Bailey
dbaileyconsultancy.co.uk