蚁群算法求函数最大值程序
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));
end
step=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)
upper_1
temp1=upper_1;
end
if temp2upper_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
end
end
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);