function [u, d, l] = decomt(u, d, l)
% usage: [u, d, l] = decomt(u, d, l)
%
% The LU decomposition of a tridiagonal matrix
% using Gaussian elimination without pivoting
%
% Inputs
%	u	the upper diagonal, overwritten by output
%	d	the main diagonal, overwritten by output
%	l	the subdiagonal, overwritten by output
% Outputs
%	u	the upper diagonal of U
%	d	the main diagonal of U
%	l	the subdiagonal of L 

n = length(d);

for i=1:n-1,
    l(i) = l(i)/d(i);			% multiplier
    d(i+1) = d(i+1) - l(i)*u(i);	% update
end