function value = cubic ( x )

%*****************************************************************************80
%
%% cubic evaluates a cubic function.
%
%  Discussion:
%
%    There is a root between 1 and 2.
%
%  Licensing:
%
%    This code is distributed under the GNU LGPL license.
%
%  Modified:
%
%    12 September 2019
%
%  Input:
%
%    real x, the argument.
%
%  Output:
%
%    real value, the function value.
%
  value = x.^3 - x - 1.0;

  return
end

