function [u,degu,v,degv] = poldiv(a,dega,b,degb)

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% polynomial division:                                    % 
%                                                         %
%    a = b*u + v,    degv<degb                            %
%                                                         %
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% M. Sebek, June 1990                                     %
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

% function used: polred; 

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

if degb<0
   error('poldiv: division by a zero polynomial');
end

u=0; degu= -Inf;
v=a; degv=dega;

while degv-degb>=0
  d=degv-degb;
  c=-v(degv+1)/b(degb+1);
  [v,degv]=polred(v,degv,b,degb,c,d);
  [u,degu]=polred(u,degu,[1],0,-c,d);
end