%
% DESCRIPTION: Generic check for a arithmetic operator unit test which
%              checks the y-errors for a single inputs.
%
% CALL:        atest = check_aop_errors(fcn, in1, in2, out);
%
% VERSION:     $Id: check_aop_errors.m,v 1.2 2010/09/21 16:50:14 ingo Exp $
%

function atest = check_aop_errors(fcn, in1, in2, out)
  if ~isempty(in1.dy) || ~isempty(in2.dy)
    
    din1 = in1.dy;
    din2 = in2.dy;
    
    if isempty(din1)
      din1 = zeros(size(in1.y));
    end
    if isempty(din2)
      din2 = zeros(size(in2.y));
    end
    
    switch func2str(fcn)
      case {'plus', 'minus'}
        dy = sqrt(din1.^2 + din2.^2);
      case {'times', 'mtimes'}
        dy = sqrt( (din1./in1.y).^2 + (din2./in2.y).^2 ) .* abs(in1.y.*in2.y);
      case {'rdivide', 'mrdivide'}
        dy = sqrt( (din1./in1.y).^2 + (din2./in2.y).^2 ) .* abs(in1.y./in2.y);
      otherwise
        dy = [];
    end
    
  else
    dy = [];
  end
  
  atest = isequal(out.dy, dy);
  
end