function [A]=chap_2_sect_6_prob_28(L,U)
% returns the product of a lower triangular matrix L and an upper trianglar matrix U
%
% Written by:
% -- 
% John L. Weatherwax                2006-03-28
% 
% email: wax@alum.mit.edu
% 
% Please send comments and especially bug reports to the
% above email address.
% 
%-----

[n,n]=size(L);
A=zeros(size(L)); 
for i=1:n,
  for j=1:n,
    for k=1:min(i,j)
      A(i,j) = A(i,j) + L(i,k) * U(k,j); 
    end
  end
end