1、

>> [x,y,z]=meshgrid(linspace(-1.3,1.3));

>> val=(x.^2+(9/4)*y.^2+z.^2-1).^3-x.^2.*z.^3-(9/80)*y.^2.*z.^3;

>> isosurface(x,y,z,val,0)

>> axis equal

>> view(-10,24)

>> colormap flag

>> camlight

>> lighting phong

2、

>> b=0:0.01*pi:2*pi;

>> a=2;

>> r=a*(1-sin(b));

>> h=polar(b,r,'r');

>> set(h,'LineWidth',6);

3、

>> a=ezplot('17*x^2-16*abs(x)*y+17*y^2-225');

>> set(a,'color','r','LineWidth',6);

4、

>> [x,y]=meshgrid(-5:0.01:5,-5:0.01:5);

>> v=17*x.^2-16*abs(x).*y+17*y.^2+150./abs(5*x+sin(5*y))<225;

>> contourf(x,y,v);

>> colormap(jet);

5、

>> [X,Y,Z] = meshgrid(linspace(-3,3,101));

>> F = -X.^2.*Z.^3-(9/80).*Y.^2.*Z.^3+(X.^2+(9/4).*Y.^2+Z.^2-1).^3;

>> hFigure = figure;

>> sz = get(hFigure, 'Position');

>> set(hFigure, 'Position', [sz(1)-0.15*sz(3) sz(2) 1.3*sz(3) sz(4)]);

>> hAxes = axes('Parent',hFigure,'NextPlot','add', 'DataAspectRatio',[1 1 1],
'XLim',[30 120],'YLim',[35 65],'ZLim',[30 75]);

>> view([-39 30]);

>> axis off

>> hidden on

>> p = patch(isosurface(F,-0.001));

>> set(p,'FaceColor','w','EdgeColor','none');

>> for iX = [35 38 41 45 48 51 54 57 61 64 67]

plane = reshape(F(:,iX,:),101,101);

cData = contourc(plane,[0 0]);

xData = iX.*ones(1,cData(2,1));

h3=plot3(hAxes,xData,cData(2,2:end),cData(1,2:end),'k');

set(h3,'color','r');

pause(.1), drawnow

end

>> for iY = [41 44 47 51 55 58 61]

plane = reshape(F(iY,:,:),101,101);

cData = contourc(plane,[0 0]);

yData = iY.*ones(1,cData(2,1));

h4=plot3(hAxes,cData(2,2:end),yData,cData(1,2:end),'k');

set(h4,'color','r');

pause(.1), drawnow

end

>> for iZ = [36 38 40 42 44 46 48 50 52 54 56 58 60 62 64 66 69 71]

plane = F(:,:,iZ);

cData = contourc(plane,[0 0]);

startIndex = 1;

if size(cData,2) > (cData(2,1)+1)

startIndex = cData(2,1)+2;

zData = iZ.*ones(1,cData(2,1));

h0=plot3(hAxes,cData(1,2:(startIndex-1)),cData(2,2:(startIndex-1)),zData,'k');

set(h0,'color','r');

end

zData = iZ.*ones(1,cData(2,startIndex));

h1=plot3(hAxes,cData(1,(startIndex+1):end),cData(2,(startIndex+1):end),zData,'k');

set(h1,'color','r');

pause(.1), drawnow

end

>> pause(.2)

>> text(7,50,70,'I',
'color','r','fontWeight','bold','FontAngle','italic','fontsize',100)

>> pause(.5)

>> text(80,50,43,'YOU','color','r'
,'fontWeight','bold','FontAngle','italic','fontsize',100)

>> pause(.2)

>> line([20 80],[50 50],[52.5 52.5], 'color','k')

>> line([50 50],[20 80],[52.5 52.5], 'color','k')

>> line([50 50],[50 50],[30 80], 'color','k')

>> text(20,50,50,'x')

>> text(48,20,50,'y')

>> text(45,50,80,'z')

>> text(30,60,30,'(x^2+9/4y^2+z^2-1)^3 - x^2z^3-9/80y^2z^3=0', 'fontsize',8)

>> text(35,45,30,'-3<3', 'fontsize',8)

6、

>> f=@(x,y,z)(x.^2+ (9./4).*y.^2 + z.^2 - 1).^3 - x.^2.*z.^3 -
(9./80).*y.^2.*z.^3;

>> [x,y,z]=meshgrid(linspace(-3,3));

>> val=f(x,y,z);

>> [p,v]=isosurface(x,y,z,val,0);

>>
patch('faces',p,'vertices',v,'facevertexcdata',jet(size(v,1)),'facecolor','w','edgecolor','flat');

>> view(3);

>> grid on;

>> axis equal;

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