exa10_11.m

有关matlab r2007的实用教程

%定义网格并绘制Z的表面图
x=0:0.16:5;
y=0:0.16:5;
[xx,yy]=meshgrid(x,y);
zz=xx.^yy-yy.^xx;
h=surf(x,y,zz);

%设置绘制属性
set(h,'EdgeColor',[0.7 0.7 0.7]);
view(20,50);
colormap(hsv);
title('z=x^y-y^x'); 
xlabel('x');
ylabel('y');
zlabel('z')
hold on;

pause
%加画方程x^y-y^x=0的曲线
c=contourc(x,y,zz,[0 0]);
list1len=c(2,1);
xContour=[c(1,2:1+ list1len) NaN c(1,3+ list1len:size(c,2))];
yContour=[c(2,2:1+ list1len) NaN c(2,3+ list1len:size(c,2))];
line(xContour,yContour,'Color','k');

pause
%绘出能使方程x^y-y^x=0的整数解，其中2^4=4^2是x~=y的惟一整数解
plot([0:5 2 4],[0:5 4 2],'r.','MarkerSize',25); 

pause
%将 (e,pi) 和 (pi,e) 两点绘制在图中可以发现e^pi和pi^e的大小，后者比前者略大一点
e=exp(1);
plot([e pi],[pi e],'r.','MarkerSize',25);
plot([e pi],[pi e],'y','MarkerSize',10);
text(e,3.5,'(e,pi)','Color','K','HorizontalAlignment','left');
text(3.3,e,'(pi,e)','Color','K','HorizontalAlignment','left');
hold off