## Copyright (C) 2013, Roberto Porcu' <roberto.porcu@polimi.it>
## Copyright (C) 2014, Jacopo Corno <jacopo.corno@gmail.com>
##
## This file is part of Octave.
##
## Octave 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 3 of the License, or (at
## your option) any later version.
##
## Octave 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 Octave; see the file COPYING.  If not, see
## <http://www.gnu.org/licenses/>.

function res = AbsRel_Norm (x, x_old, AbsTol, RelTol, normcontrol, y)

  n = length (x);

  if (nargin == 5)
    y = zeros (size (x));
  elseif (nargin != 6)
    error ("OdePkg:InvalidArgument",
           "invalid number of input arguments");
  endif

  if (length (x_old) != n
      || length (y) != n)
    error ("OdePkg:InvalidArgument",
           "invalid dimensions of input arguments");
  endif
  
  if ((length (AbsTol) != 1 && length (AbsTol) != n)
      || (length (RelTol) != 1 && length (RelTol) != n))
    error ("OdePkg:InvalidArgument",
           "invalid dimensions of input arguments");
  endif
  
  sc = AbsTol + max (abs (x), abs (x_old)) .* RelTol;
  if (normcontrol)
    res = max (abs (x - y) ./ sc);
  else
    res = sqrt ((1 / n) * sum (((x - y) ./ sc).^2));
  endif

endfunction