anchor.diff:  rat := num / den;
   
   downsphere := NewMarkedSphere([P1zero,P1one,P1infinity]);
  +
  + P1PreImages(x^4 + 11*x^3 - 29*x^2 + 11*x + 1, P1zero); # above 0
  +  P1PreImages(x^5 - 25/16*x^4 + 75/32*x^3 - 25/64*x^2 + 5/64*x + 1/64,P1zero);
  +  P1PreImages(x, P1zero); # above infinity
  +  P1PreImages(x+1, P1zero);
  +  P1PreImages(x^2 - 3/2*x + 1, P1zero);
  +  P1PreImages(x^3 - 4*x^2 + 5/4*x + 1/8, P1zero);
  +P1PreImages(28672*x^20-2114560*x^19+13722240*x^18-65614080*x^17+245351840*x^16-660267008*x^15+1248458280*x^14-1700835920*x^13+1704958640*x^12-1267574420*x^11+690436992*x^10-257110380*x^9+52736995*x^8-948040*x^7-1171555*x^6-246148*x^5+86660*x^4+11060*x^3-1520*x^2-240*x-8,
  +P1zero);
  +
  +
   
   upsphere := NewMarkedSphere(Concatenation([
     P1PreImages(x^4 + 11*x^3 - 29*x^2 + 11*x + 1, P1zero), # above 0
  
positive.code: P1zero)])); # above 1
  
   SetInfoLevel( InfoIMG , 3 );
  
  biset := SphereMachineOfBranchedCovering(downsphere, upsphere, rat);
  
  
negative.code: 
  
  LoadPackage("IMG");
  
   bitPrecision := 600;
  
   PushOptions( rec(bits:=bitPrecision) );
  
   SetP1Points( MPC, bitPrecision );
  
   MAKEP1EPS@IMG();
  
  
  x := P1z;
  
  num := 50176 * (x^4 + 11*x^3 - 29*x^2 + 11*x + 1)^5 *
  