Hi Brandon -

This is indeed a bug in NetLogo, I have fixed it for the next release.

thanks for the report.


On Thu, 27 Apr 2006 brich at nd.edu wrote:

Hey guys,

I think I may have come across a bug in Netlogo 3.1.  For reference, here's the
output of my System tab on the About dialog:

NetLogo 3.1 (April 14, 2006)
Java VM: 1.5.0_06 (Sun Microsystems Inc.; 1.5.0_06-b05)
operating system: Windows XP 5.1 (x86 processor)
Java heap: used = 33 MB, free = 38 MB, max = 508 MB

JOGL: (3D View not initialized)
OpenGL Graphics: (3D View not initialized)

The model I'm creating requires me to find a turtle's nearest neighbor (which
would be an EXCELLENT function to include in the next version!).  To do this, I
have the turtle search an ever-expanding radius and, once neighbors are found, I
select the one with the smallest distance-to.  However, I found that certain
outlying turtles would cause this function to loop until the radius was so
large it caused an overflow error (negative radius value).  The attached
model demonstrates why.  After about radius=150, the in-radius function stops
being a circle and starts to flatten out, such that the radius never increases,
nore matter how big you make it.

I did some testing and found that this is only an issue when vertical wrapping
is OFF (as it is in my model).   The dimensions of the space don't seem to make
a difference, just the v-wrap attribute.  Take a look and let me know that you


Brandon Rich
University of Notre Dame

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