function [ x ] = fs(A)
[r c]=size(A);
x=zeros(r,1);
for j=1:r
    y(j,1)=A(j,r+1);
    for k= 1:j-1
        y(j,1)=y(j,1)-A(j,k)*x(k,1);
    end
    x(j,1)=y(j,1)/A(j,j);
end
end

