function A=lugauss(A)
%LUGAUSS LU factorization without pivoting.
% A = LUGAUSS(A) stores an upper triangular matrix in
% the upper triangular part of A and a lower triangular
% matrix in the strictly lower part of A (the diagonal
% elements of L are 1).
[n,m]=size(A);
if n ~= m; error('A is not a square matrix'); else
 for k = 1:n-1
  for i = k+1:n
   A(i,k) = A(i,k)/A(k,k);
   if A(k,k) == 0, error('Null diagonal element'); end
   j = [k+1:n]; A(i,j) = A(i,j) - A(i,k)*A(k,j);
  end
 end
end