doolittle分解 二分法求根matlab

A=[1 2 3 -4 -2;-3 -4 -12 13 5;2 10 0 -3 10;4 14 9 -13 7];%A为系数矩阵

for i=2:4
for j=i:5
for k=1:(i-1)
A(i,j)=A(i,j)-A(i,k)*A(k,j);
end
end
for j=(i+1):4
for k=1:(i-1)
A(j,i)=A(j,i)-A(j,k)*A(k,i);
end
A(j,i)=A(j,i)/A(1,i);
end
end
for i=1:4
for j=1:5
if(i<j)
L(i,j)=0;
R(i,j)=A(i,j);
else if(i==j)
L(i,j)=1;
R(i,j)=A(i,j);
else L(i,j)=A(i,j);
R(i,j)=0;
end
end
end
end
L,R

保存为m文件
主窗口运行*.m得到：
L =

1 0 0 0 0
-3 1 0 0 0
2 3 1 0 0
4 3 2 1 0

R =

1 2 3 -4 -2
0 2