function x=lufjf(a,b)
[l,u,p]=lu(a);
n=size(a,1);
b=p*b;
for i=1:n
    c=0;
    for r=1:(i-1)
        c=c+l(i,r)*y(r);
    end
    y(i)=b(i)-c
end
for i=1:n
    k=n-i+1;
    d=0;
    for r=(k+1):n
    d=d+u(k,r)*x(r);
end
x(k)=(y(k)-d)/u(k,k)
end