function [x] = myLU(A,b)
%Gaussian elimination first
for i=1:n-1
%ith step
    for k=i+1:n
    %kth row
        multiplier = A(k,i)/A(i,i);
        for j=i+1:n
            A(k,j)=A(k,j)-multiplier*A(i,j)
        end

        for j=i+1:n
            b(j)=b(j)-multiplier*b(i);
        end
    end
end
%upper triangular
for i=n:-1:1
    %solve for x(i), assume x(i+1)...x(n) are known
    x(i)=b(i);
    for k=i+1:n
        x(i)=x(i)-A(i,k)*x(k);
    end
    x(i)=x(i)/A(i,i);
end