Uniform Distribution on a Sphere Example 3D

1 collaborator

Uri Wilensky (Author)

WHAT IS IT?

This code example demonstrates the correct way to uniformly distribute turtles on the surface of a sphere. Note that simply setting the heading and pitch to random numbers between 0 and 360 results in a non-uniform distribution with clustering at the poles in the z direction. The solution in SETUP-UNIFORM is based on information found here:

http://mathworld.wolfram.com/SpherePointPicking.html

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to setup-uniform
 ca
 crt number
 [
   ;; remember that turtles automatically have a random heading when created
   tilt-up asin (1.0 - random-float 2.0)
   jump max-pxcor
   roll-right random-float 360
 ]
 do-plot
end 

to setup-not-uniform
 ca
 crt number
 [
   ;; remember that turtles automatically have a random heading when created
   tilt-up random-float 360
   jump max-pxcor
   roll-right random-float 360
 ]
 do-plot
end 

to do-plot
  set-current-plot "xcor"
  set-current-plot-pen "xcor"
  histogram [ xcor ] of turtles
  set-current-plot "ycor"
  set-current-plot-pen "ycor"
  histogram [ ycor ] of turtles
  set-current-plot "zcor"
  set-current-plot-pen "zcor"
  histogram [ zcor ] of turtles
end 


; Copyright 2007 Uri Wilensky. This code may be freely copied, distributed,
; altered, or otherwise used by anyone for any legal purpose.

There are 3 versions of this model.

Uploaded by	When	Description	Download
Uri Wilensky	over 14 years ago	Updated from NetLogo 4.1	Download this version
Uri Wilensky	over 14 years ago	Model from NetLogo distribution	Download this version
Uri Wilensky	over 14 years ago	Uniform Distribution on a Sphere Example 3D	Download this version

Attached files

File	Type	Description	Last updated
Uniform Distribution on a Sphere Example 3D.png	preview	Preview for 'Uniform Distribution on a Sphere Example 3D'	over 11 years ago, by Uri Wilensky	Download

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