lufenjie.m

这是线性议程组的直接解法

function [L,U]=LUFenjie(A)
if inv(A)==0
    disp('不满足条件！');
end
[h,k]=size(A);
LL=eye(h);
A1=A;
for k=1:h-1
    L=eye(h);
    [m,d]=max(A1(:,k));
    if d~=k && d>k
        temp=A1(d,:);
        A1(d,:)=A1(:,k);
        A1(k,:)=temp;
    end
    L(k+1:h,k)=A1(k+1:h,k)/A1(k,k);
    A1=L*A1;
    LL=LL*L;
end
L=LL;
U=inv(L)*A;
end