1. çéå¼å·ç¹çµè·çµåºä¸çµå¿åå¸
[x,y]=meshgrid(-2:0.1:2,-2:0.1:2);
%以0.1为æ¥é¿å»ºç«å¹³é¢æ°æ®ç½æ ¼
z=1./sqrt((x-1).^2+y.^2+0.01)... %ååºçµå¿è¡¨è¾¾å¼
-1./sqrt((x+1).^2+y.^2+0.01);
[px,py]=gradient(z);
%æ±çµå¿å¨x,yæ¹åç梯度å³çµåºå¼ºåº¦
contour(x,y,z,[-12,-8,-5,-3,-1,... %ç»åºçå¿çº¿
-0.5,-0.1,0.1,0.5,1,3,5,8,12])
hold on %ä½å¾æ§å¶
quiver(x,y,px,py,'k') %ç»åºåç¹ä¸çµåºç大å°åæ¹å
2. çéåå·ç¹çµè·ççµåºçº¿çç»å¶
ä¸é¢æ¯åå¾®åæ¹ç¨çå½æ°æ件ï¼
function ydot=dcx1fun(t,y,flag,p1,p2)
%p1,p2æ¯åéï¼è¡¨ç¤ºçµé
ydot=[p1*(y(1)+2)/(sqrt((y(1)+2).^2+y(2).^2).^3)+...
p2*(y(1)-2)/(sqrt((y(1)-2).^2+y(2).^2).^3);
%dx/dt=Ex
p1*y(2)/(sqrt((y(1)+2).^2+y(2).^2).^3)+...
p2*y(2)/(sqrt((y(1)-2).^2+y(2).^2).^3)];
%dy/dt=Ey
ç¼å好å½æ°æ件åï¼å½å为dcx1fun.måå¨å½åè·¯å¾ä¸ï¼ç¶åå¼å§ç¼å解微åæ¹ç¨ç主ç¨åºdcx1.mï¼
p1=10; p2=10; %ç¹çµè·æ带çµé
axis([-5,5,-5,5]); %设å®åæ è½´èå´ -5â¤xâ¤5,-5â¤yâ¤5
hold on %å¾å½¢æ§å¶,ä¸å¯æ¦é¤æ¨¡å¼
plot(2,0,'*r'); plot(-2,0,'*r') %ç»å¶ä¸¤æºçµè·
a=(pi/24):pi/12:(2*pi-pi/24);
%åå¨ä¸çµåºçº¿èµ·ç¹æ对åºçè§åº¦
b=0.1*cos(a);c=0.1*sin(a);
%çµåºçº¿èµ·ç¹æ对åºçç¸å¯¹åæ
b1=-2+b;b2=2+b; %æèµ·ç¹åå¨çåå¿æ¾ç½®å¨æºçµè·å¤
b0=[b1 b2]; c0=[c c]; %åå§æ¡ä»¶ï¼ææçµåºçº¿çèµ·ç¹
%ç横ã纵åæ ææäºç¢éb0åc0
for i=1:48 %循ç¯æ±è§£48次微åæ¹ç¨
[t,y]=ode45('dcx1fun',[0:0.05:40],[b0(i),c0(i)],[ ],p1,p2);
%è°ç¨ode45æ±è§£ï¼å¯¹åºä¸ä¸ªåæ¡ä»¶ï¼èµ·ç¹ï¼ï¼æ±è§£åºä¸æ¡çµåºçº¿
plot(y(:,1),y(:,2),'b') %ç»å¶åºæ¤æ¡çµåºçº¿
end %ç»æ循ç¯ï¼å
±ç»å¶åº48æ¡çµåºçº¿
åèäºãMatlab å¨åºç¡ç©çå¦ä¸çåºç¨ã
http://bnucourse.bnu.edu.cn/course/physics/05/jcwlxshyjy.pdf