function b = rco_forward_sub(A,b)
% RCO_FORWARD_SUB - Recursive column oriented forward substitution (lower trianglar matrix)
% 
% Written by:
% -- 
% John L. Weatherwax                2006-10-25
% 
% email: wax@alum.mit.edu
% 
% Please send comments and especially bug reports to the
% above email address.
% 
%-----

b(1) = b(1)/A(1,1); 
if( length(b)==1 ) return; end
b(2:end) = b(2:end) - A(2:end,1)*b(1); 
b(2:end) = rco_forward_sub(A(2:end,2:end),b(2:end));