import math;
import graph3;
import palette;

size3(8cm,8cm,3cm,IgnoreAspect);
size(8cm,0);

currentprojection=perspective(camera=(9.73,1.26,2.31));

real a=1;
real f(pair z){
   real tempo=0.01-((z.x^2+z.y^2)^2-a^2*(z.x^2-z.y^2))^2;
   if(tempo>=0) return sqrt(tempo);
   else return 0;
   }
limits((-1.3,-.55,-.05),(1.4,.55,.4));
 xaxis3(Label("$x$",1),blue,arrow=Arrow3);
 yaxis3(Label("$y$",1) ,blue,arrow=Arrow3);
 zaxis3(Label("$z$",1),blue,arrow=Arrow3);

surface s=surface(f,(-1.1,-.5),(1.1,.5),95,75,monotonic);

draw(s,yellow,black);