M=10000;
a(1,:)=[0,50,M,40,25,10];
a(2,:)=[zeros(1,2),15,20,M,25];
a(3,:)=[zeros(1,3),10,20,M];
a(4,:)=[zeros(1,4),10,25];
a(5,:)=[zeros(1,5),55];
a(6,:)=zeros(1,6);
a=a+a';
解读以下程序
pb(1:length(a))=0;
pb(1)=1;
index1=1;
index2=ones(1,length(a));
d(1:length(a))=M;d(1)=0;temp=1;
while sum(pb)<length(a)
   tb=find(pb==0);
   d(tb)=min(d(tb),d(temp)+a(temp,tb));
tmpb=find(d(tb)==min(d(tb)));
   temp=tb(tmpb(1));
   pb(temp)=1;
index1=[index1,temp];
   index=index1(find(d(index1)==d(temp)-a(temp,index1)));
   if length(index)>=2
      index=index(1);
   end
   index2(temp)=index;
end
d, index1, index2

麻烦大神帮我解读一下！！！！谢谢！