# Main Command: Go
# Bifurication by Guy Walker
# www.logoarts.co.uk

to new
  # set default screen, pen and turtle 
  ResetAll SetScreenSize [400 400] HideTurtle 
  SetSC Black SetPC Green SetPS 1 PenUp 
end

to init
  # change the start and end for magnified plots 
  Make "Start 1 Make "End 4
  Make "Step (:End-:Start)/360
end

to function :k :x
Output :K*:X * (1-:X)
end

to display
  # write header title and footer values
  PenUp SetPC White SetH 0
  SetPos [-190 182] Label [Bifurcation Diagram]
  SetPos [-190 -190] Label ( List "k\ = :Start "to :End )
end

to go
  New Init Display SetPC Green
  Make "X 0.1 Make "K :Start
  # first iterate to eliminate transients 
  Repeat 128 [
    Make "Xn Function :K :X
    Make "X :Xn]
  # actual iteration 
  For (List "K :Start :End :Step) [
    Repeat 64 [
      Make "Xn Function :K :X
      Make "X :Xn
      # calculate horiz x
      Make "Xh (360/(:End-:Start))*:K-180-((360/(:End-:Start))*:Start)
      Dot List :Xh (360*:X)-180] ]
end