f=@(x,y,z)(x.^2+9/4*y.^2+z.^2-1).^3-x.^2.*z.^3-9/80*y.^2.*z.^3
implicitmesh(f,[-5 5],150)
-----------------------------
function h=implicitmesh(f,xlimit,ylimit,zlimit,gd)
%implicitmesh(f,span,gd):画隐函数曲面f(x,y,z)=0的网格图,
% 各坐标范围均限定在span=[lb,ub],
% 网格数为gd,默认为25
if nargin==2
ylimit=xlimit;zlimit=xlimit;gd=25;
elseif nargin==3
gd=ylimit;ylimit=xlimit;zlimit=xlimit;
elseif nargin==4
gd=25;
elseif nargin==5
else
error('Error in input arguments')
end
x=linspace(xlimit(1),xlimit(2),gd);
y=linspace(ylimit(1),ylimit(2),gd);
z=linspace(zlimit(1),zlimit(2),gd);
[x,y,z]=meshgrid(x,y,z);val=f(x,y,z);
[f,v]=isosurface(x,y,z,val,0);
if isempty(f)
warning('There is no graph in the range.');
p=[];
else
newplot;
p=patch('Faces',f,'Vertices',v,'CData',v(:,3),'facecolor','w','EdgeColor','flat');
isonormals(x,y,z,val,p);view(3);grid on
end
if nargout==0
else
h=p;
end
