function d = p03_fd ( p )

%*****************************************************************************80
%
%% P03_FD is a signed distance function for problem 3.
%
%  Licensing:
%
%    (C) 2004 Per-Olof Persson. 
%    See COPYRIGHT.TXT for details.
%
%  Modified:
%
%    06 February 2006
%
%  Parameters:
%
%    Input, real P, one or more points.
%
%    Output, real D, the signed distance of each point to the boundary of the region.
%
  d1 = drectangle ( p, -1.0, 1.0, -1.0, 1.0 );
  d2 = dcircle ( p, 0.0, 0.0, 0.4 );

  d = ddiff ( d1, d2 );

  return
end