蚁群算法求函数最大值的程序(共3页).doc

精选优质文档-倾情为你奉上function maxx,maxy,maxvalue=antcolony% 蚁群算法求函数最大值的程序% 初始化ant=200; % 蚂蚁数量times=50; % 蚂蚁移动次数rou=0.8; % 信息素挥发系数p0=0.2; % 转移概率常数lower_1=-1; % 设置搜索范围upper_1=1; %lower_2=-1; %upper_2=1; %for i=1 : ant X(i,1)=(lower_1+(upper_1-lower_1)*rand); %随机设置蚂蚁的初值位置 X(i,2)=(lower_2+(upper_2-lower_2)*rand); tau(i)=F(X(i,1),X(i,2);endstep=0.05;f='-(x.2+2*y.2-0.3*cos(3*pi*x)-0.4*cos(4*pi*y)+0.7)'x,y=meshgrid(lower_1:step:upper_1,lower_2:step:upper_2);z=eval(f);figure(1);mesh(x,y,z);hold on;plot3(X(:,1),X(:,2),tau,'k*')hold on;text(0.1,0.8,-0.1,'蚂蚁的初始分部位置')xlabel('x');ylabel('y');zlabel('f(x,y)');for t=1:times lamda=1/t; tau_best(t),bestindex=max(tau); for i=1:ant p(t,i)=(tau(bestindex)-tau(i)/tau(bestindex); % 计算状态转移概率 end for i=1:ant if p(t,i)<p0 %局部搜索 temp1=X(i,1)+(2*rand-1)*lamda; temp2=X(i,2)+(2*rand-1)*lamda; else %全局搜索 temp1=X(i,1)+(upper_1-lower_1)*(rand-0.5); temp2=X(i,2)+(upper_2-lower_2)*(rand-0.5); end % 越界处理 if temp1<lower_1 temp1=lower_1; end if temp1>upper_1 temp1=upper_1; end if temp2<lower_2 temp2=lower_2; end if temp2>upper_2 temp2=upper_2; end % if F(temp1,temp2)>F(X(i,1),X(i,2) % 判断蚂蚁是否移动 X(i,1)=temp1; X(i,2)=temp2; end end for i=1:ant tau(i)=(1-rou)*tau(i)+F(X(i,1),X(i,2); % 更新信息量 endend figure(2);mesh(x,y,z);hold on;x=X(:,1);y=X(:,2);plot3(x,y,eval(f),'k*')hold on;text(0.1,0.8,-0.1,'蚂蚁的最终分布位置')xlabel('x');ylabel('y'),zlabel('f(x,y)');max_value,max_index=max(tau);maxx=X(max_index,1);maxy=X(max_index,2);maxvalue=F(X(max_index,1),X(max_index,2);function F=F(x1,x2) %目标函数F=-(x1.2+2*x2.2-0.3*cos(3*pi*x1)-0.4*cos(4*pi*x2)+0.7);专心-专注-专业