clear
clc
Ab=xlsread('data3_4.xls');
[m,nb]=size(Ab);
n=nb-1;
A=Ab(:,1:n);
b=Ab(:,nb);
Ab(2:m,1)=Ab(2:m,1)/Ab(1,1);
for k=2:m
    for j=k:nb
        for q=1:k-1
            Ab(k,j)=Ab(k,j)-Ab(q,k)*Ab(q,j)/Ab(q,q);
        end
    end
    for i=k+1:m
        Ab(i,k)=Ab(k,i)/Ab(k,k);
    end
end
x=zeros(n,1);
x(n)=Ab(n,nb)/Ab(n,n);
for k=n-1:-1:1
    x(k)=(Ab(k,nb)-Ab(k,k+1:n)*x(k+1:n,1))/Ab(k,k);
end
for k=1:n
    fprintf('x[%d]=%f\n',k,x(k));
end