差分算法解决函数最值问题

function [Pb,trace]=DE D=30;%维数 NP=40;%NP为种群规模---- F=0.5;%交叉因子 CR=0.1;%交叉概率 eps=1e-9;%精度 gen_max=500;%最大进化代数 trace=zeros(gen_max,2); bounds=100*ones(D,2); bounds(:,1)=-1*bounds(:,1); rng=(bounds(:,2)-bounds(:,1))'; x=(ones(NP,1)*rng).*(rand(NP,D))+(ones(NP,1)*bounds(:,1)');%初始种群 count=1; trial=zeros(1,D); cost=zeros(1,NP); cost(1)=fitness(x(1,:),D); Pb=cost(1);%存放最优值 Xb=x(1,:);%存放最优位置 for i=2:NP cost(i)=fitness(x(i,:),D); if(cost(i)<=Pb) Pb=cost(i); Xb=x(i,:); end end trace(1,1)=1; trace(1,2)=Pb; while(count<gen_max)%count<gen_max abs(Pb)>eps for i=1:NP while 2>1 a=floor(rand*NP)+1; if a~=i break; end end while 2>1 b=floor(rand*NP)+1; if b~=i&b~=a break; end end while 2>1 c=floor(rand*NP)+1; if c~=i&c~=a&c~=b break; end end jrand=floor(rand*D+1); for k=1:D if(rand<CR|jrand==k) trial(k)=x(c,k)+F*(x(a,k)-x(b,k)); else trial(k)=x(i,k); end if trial(k)<bounds(k,1) trial(k)=bounds(k,1); end if trial(k)>bounds(k,2) trial(k)=bounds(k,2); end end score=fitness(trial(:),D); if(score<=cost(i)) x(i,1:D)=trial(1:D); cost(i)=score; end if cost(i)<=Pb Pb=cost(i); Xb(1:D)=x(i,1:D); end end count=count+1; trace(count,1)=count; trace(count,2)=Pb; end %--------------结束搜索--------------- count; Pb; Xb; %-------函数值计算----------------------- function eval=fitness(x,D) sol=x; eval=0; for i=1:D eval=eval+sol(i)^2; end %----------------------------------------------