blob16

1; # Prevent Octave from thinking that this is a function
   # though one is defined here
   
  function w = f(x2,y2,z2,c,r,e) 
   x  = (x2-c(1))/r(1);
   y  = (y2-c(2))/r(2);
   z  = (z2-c(3))/r(3);
   # function at origin must be <0, and >0 far enough away.  w=0 defines the surface
   fx = 1.7*atan(x/1.7);  
   fy = y+0.03*x.^3;
   fz = z;    
   w = sqrt(((fx-1)/1).^2+((fy-1)/1).^2+((fz-0)/1).^2) -1;

   endfunction;