DescriptionDiffraction beats.gif	English: Animation of the node lines of the diffraction pattern of two sources that have a small difference in frequency; made because of Steven Waller's theory about Stonehenge
Date	March 2012
Source	Own work
Author	Pieter Kuiper
Permission (Reusing this file)	Public domainPublic domainfalsefalse I, the copyright holder of this work, release this work into the public domain. This applies worldwide. In some countries this may not be legally possible; if so: I grant anyone the right to use this work for any purpose, without any conditions, unless such conditions are required by law. Category:Self-published work#Diffraction%20beats.gifCategory:PD-self#Diffraction%20beats.gif

 This diagram was created with Mathematica by n.

Mathematica code:

d = 5; r1[x_, y_] = Sqrt[x^2 + (y - d)^2]; r2[x_, y_] = Sqrt[x^2 + (y + d)^2]; node[x_, y_] = r1[x, y] - r2[x, y]; Export["Diffraction_beats.gif", Table[ContourPlot[{node[x, y] == 1 + a, node[x, y] == -1 + a, node[x, y] == 3 + a, node[x, y] == -3 + a, node[x, y] == 5 + a, node[x, y] == -5 + a, node[x, y] == 7 + a, node[x, y] == -7 + a, node[x, y] == 9 + a, node[x, y] == -9 + a}, {x, -20, 20}, {y, -20, 20}, ContourStyle -> Directive[Black, Thick]], {a, -1.0, 1.0, 0.1}]]