

  BOTELLA de Klein 02 
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  http://perso.club-internet.fr/rferreol/encyclopedie/surfaces/klein/klein.shtml 


  p = 2*PI*Q                              2*PI*Q < = PI  -->  Q = 0...1/2
  q = 2*PI*K
  r = 4*(1-cos(p)/2)

  x1 = 6*cos(p)*(1+sin(p)) +r*cos(p)*cos(q)
  x2 = 6*cos(p)*(1+sin(p)) -r*cos(q)             x = (( p < = PI ) ?x1:x2)
 
  y1 = 16*sin(p) +r*sin(p)*cos(q)
  y2 = 16*sin(p)                                 y = (( p < = PI ) ?y1:y2)
  
  z = r*sin(q) 
