function [i,j]=getindxn(R,Idx);
%GETINDXN
%
%[i,j]=getindxn(R,Idx)


% Copyright (C) 1995-2006  Rasmus Bro & Claus Andersson
% Copenhagen University, DK-1958 Frederiksberg, Denmark, rb@life.ku.dk
%
% This program is free software; you can redistribute it and/or modify it under 
% the terms of the GNU General Public License as published by the Free Software 
% Foundation; either version 2 of the License, or (at your option) any later version.
%
% This program is distributed in the hope that it will be useful, but WITHOUT 
% ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS 
% FOR A PARTICULAR PURPOSE.  See the GNU General Public License for more details.
% You should have received a copy of the GNU General Public License along with 
% this program; if not, write to the Free Software Foundation, Inc., 51 Franklin 
% Street, Fifth Floor, Boston, MA  02110-1301, USA.

l=size(Idx,2);

i=Idx(1);
j=Idx(2);

if l==3,
  j = j + R(2)*(Idx(3)-1);
 else
  for q = 3:l,
    j = j + prod(R(2:(q-1)))*(Idx(q)-1);
  end;
end;
