aUCBLogo Demos and Tests / electricfieldgradient

be electricfieldgradient
   singleshot=Name? "framenr
   ang=10^ -10
   elementarladung=1.60217733e-19
   epsilon0=float 8.854187817e-12

   ga=5.69*ang
   gb=ga
   gc_=7.48*ang

   hT
   perspective
;   axes
   PU
   pr Eges (list 0 0 0)
   eps=ang/10000
   xx=Vxx
   yy=Vyy
   zz=Vzz
   pr xx
   pr yy
   pr zz
   m=(list xx yy zz)
   m=hauptachsentrafo m
   pr m
;   vnn=reverse mergesort abs (list (m.1).1 (m.2).2 (m.3).3)
   vnn=abs (list (m.1).1 (m.2).2 (m.3).3)
   pr vnn
   pr (vnn.1-vnn.2)/vnn.3

   rotatescene2

   be xRb i j k
      output (list ga 0 0)*i+(list ga/2 ga*(sqrt 3)/2 0)*j+(list 0 0 gc_)*k
   end

   be xFe i j k
      output (xRb i j k)+(list 0 0 gc_/2)
   end

   be xMo1 i j k
      output (xRb i j k)+(list ga/2 ga*(sqrt 3)/6 gc_/4)
   end

   be xMo2 i j k
      output (xRb i j k)+(list ga/2 ga*(sqrt 3)/6 gc_*3/4)
   end

   be xMo3 i j k
      output (xRb i j k)+(list ga ga*(sqrt 3)/3 gc_/4)
   end

   be xMo4 i j k
      output (xRb i j k)+(list ga ga*(sqrt 3)/3 gc_*3/4)
   end

   be E r r0 Q
      setPenColor abs Q
      setPosXYZ r0*10/ang
      Sphere 5
      if (Norm r0)==0 [output 0]
      output (r-r0)/(Norm (r-r0))^3*elementarladung*Q/(4*pi*epsilon0)
   end

   be Eges r
      feld=(list 0 0 0)
      imax=1
      jmax=imax
      kmax=imax
      for [i -imax imax]
      [   for [j -jmax jmax]
         [   for [k -kmax kmax]
            [
               ifelse k==kmax
               [
                  feld=feld
                     +(E r xRb i j k 1)
               ][
                  ifelse i==imax or2 j==jmax
                  [
                     feld=feld
                        +(E r xRb i j k 1)
                        +(E r xFe i j k 3)
                  ][
                     feld=feld
                        +(E r xRb i j k 1)
                        +(E r xFe i j k 3)
                        +(E r xMo1 i j k -2)
                        +(E r xMo2 i j k -2)
                        +(E r xMo3 i j k -2)
                        +(E r xMo4 i j k -2)
                  ]
               ]
            ]
         ]
      ]
      output feld
   end

   be Vxx
      output ((Eges (list eps 0 0))-Eges (list -eps 0 0))/(2*eps)
   end

   be Vyy
      output ((Eges (list 0 eps 0))-Eges (list 0 -eps 0))/(2*eps)
   end

   be Vzz
      output ((Eges (list 0 0 eps))-Eges (list 0 0 -eps))/(2*eps)
   end
end