function [inb,otb] = passing(inb,otb,e,l)
%
%  returns updated basis with variables passing
%
%  on entry:
%    inb       indices to variables in the basis;
%    otb       indices to variables outside the basis;
%    e         variable entering the basis;
%    l         variable leaving the basis.
%
%  on return:
%    inb       indices to variables in the basis;
%    otb       indices to variables outside the basis.
%
n = length(otb);
for i=1:n
  if (otb(i) == e)
     otb(i) = inb(l);
     break;
  end;
end;
inb(l) = e;