function inside = circle_imp_contains_point_2d ( r, center, p )

%*****************************************************************************80
%
%% CIRCLE_IMP_CONTAINS_POINT_2D: implicit circle contains a point in 2D?
%
%  Discussion:
%
%    An implicit circle in 2D satisfies:
%
%      ( X - CENTER(1) )**2 + ( Y - CENTER(2) )**2 = R**2
%
%  Licensing:
%
%    This code is distributed under the GNU LGPL license.
%
%  Modified:
%
%    09 January 2005
%
%  Author:
%
%    John Burkardt
%
%  Parameters:
%
%    Input, real R, the radius of the circle.
%
%    Input, real CENTER(2,1), the center of the circle.
%
%    Input, real P(2,1), the point to be checked.
%
%    Output, logical INSIDE, is TRUE if the point is inside or on the circle,
%    FALSE otherwise.
%
  if ( ( p(1,1) - center(1,1) ) * ( p(1,1) - center(1,1) ) ...
     + ( p(2,1) - center(2,1) ) * ( p(2,1) - center(2,1) ) <= r * r )
    inside = 1;
  else
    inside = 0;
  end

  return
end
