    function [x] = spLsolv(L, b, list) 
%%  function [x] = spLsolv(L, b, list) 
n = size(L,1);
%%-------------------- Solve according to list
  x = b;
for k = 1:length(list)
  j = list(k); 
  x = x - x(j)*L(:,j);
end

