function L=decomL(A)
[n,m]=size(A);
L=zeros(n,m);
if n~=m
disp('error:n~=m');
return;
end
for k=1:n
L(k,k)=sqrt(A(k,k)-L(k,1:k-1)*L(k,1:k-1)');
for j=k+1:n
L(j,k)=(A(j,k)-L(j,1:k-1)*L(k,1:k-1)')/L(k,k);
end
end
end