function lambda = involutory_eigenvalues ( n )

%*****************************************************************************80
%
%% involutory_eigenvalues() returns the eigenvalues of the involutory matrix.
%
%  Licensing:
%
%    This code is distributed under the MIT license.
%
%  Modified:
%
%    19 October 2007
%
%  Author:
%
%    John Burkardt
%
%  Input:
%
%    integer N, the order of A.
%
%  Output:
%
%    real LAMBDA(N,1), the eigenvalues.
%
  lambda = zeros ( n, 1 );

  k = floor ( n / 2 );

  lambda(1:k,1) =   +1.0;
  lambda(k+1:n,1) = -1.0;

  return
end
