www.pudn.com > MATLABpro.rar > giassl.m

%a=[0.003000,59.14;5.291,-6.130];%系数矩阵a1 
%b=[59.17,46.78]'; 
%a=[1,-1,2,-1;2,-2,3,-3;1,1,1,0;1,-1,4,3];%系数矩阵a 
%b=[-8,-20,-2,4]'; 
a=[0.012,0.01,0.167;1,0.8334,5.91;3200,1200,4.2]; 
b=[0.6781,12.1,981]'; 
n=length(b); 
for k=1:n-1 
    p=find(abs(a(k:n,k))==max(abs(a(k:n,k))));    
    p=p+k-1;%我思考的主要部分！！不容易啊 
    if(p~=k) 
      t=a(k,:); 
      a(k,:)=a(p,:); 
      a(p,:)=t; 
      u=b(k); 
      b(k)=b(p); 
      b(p)=u; 
    end 
     m(k+1:n,k)=a(k+1:n,k)./a(k,k); 
     a(k+1:n,k:n)=a(k+1:n,k:n)-m(k+1:n,k)*a(k,k:n); 
     b(k+1:n)=b(k+1:n)-m(k+1:n,k)*b(k);   
end 
x(n)=b(n)/a(n,n); 
for i=n-1:-1:1 
    sum=0; 
    for j=i+1:n 
        sum=sum+a(i,j)*x(j); 
    end 
    x(i)=(b(i)-sum)/a(i,i); 
end 
jie=x'