gauss.m

追赶法

function x=gauss(A,b) 
%x=gauss(A,b) 
n=length(A); 
a=[A,b]; 
for k=1:n-1 
    maxa=max(abs(a(k:n,k))); 
    if maxa==0 
        return; 
    end 
    for i=k:n
         if abs(a(i,k))==maxa
             y=a(i,k:n+1);a(i,k:n+1)=a(k,k:n+1);a(k,k:n+1)=y;
             break;
         end
     end
     for i=k+1:n
         l(i,k)=a(i,k)/a(k,k);
         a(i,k+1:n+1)=a(i,k+1:n+1)-l(i,k).*a(k,k+1:n+1);
     end
 end
 %???ú
 if a(n,n)==0
     return
 end
 x(n)=a(n,n+1)/a(n,n);
 for i=n-1:-1:1
     x(i)=(a(i,n+1)-sum(a(i,i+1:n).*x(i+1:n)))/a(i,i);
 end