function [ n_data, x, fx ] = cot_values ( n_data )

%*****************************************************************************80
%
%% cot_values() returns some values of the cotangent function.
%
%  Discussion:
%
%    In Mathematica, the function can be evaluated by:
%
%      Cot[x]
%
%  Licensing:
%
%    This code is distributed under the MIT license.
%
%  Modified:
%
%    16 March 2010
%
%  Author:
%
%    John Burkardt
%
%  Reference:
%
%    Milton Abramowitz, Irene Stegun,
%    Handbook of Mathematical Functions,
%    National Bureau of Standards, 1964,
%    ISBN: 0-486-61272-4,
%    LC: QA47.A34.
%
%    Stephen Wolfram,
%    The Mathematica Book,
%    Fourth Edition,
%    Cambridge University Press, 1999,
%    ISBN: 0-521-64314-7,
%    LC: QA76.95.W65.
%
%  Input:
%
%    integer N_DATA.  The user sets N_DATA to 0 before the first call.  
%    Thereafter, it should simply be the value returned by the previous call.
%
%  Output:
%
%    integer N_DATA.  On each call, the routine increments N_DATA by 1, and
%    returns the corresponding data; when there is no more data, the
%    output value of N_DATA will be 0 again.
%
%    real X, the argument of the function.
%
%    real FX, the value of the function.
%
  n_max = 15;

  fx_vec = [ ...
   11.972209353628661620, ...
    3.7320508075688772935, ...
    1.8304877217124519193, ...
    1.7320508075688772935, ...
    1.0000000000000000000, ...
    0.64209261593433070301, ...
    0.57735026918962576451, ...
    0.26794919243112270647, ...
    0.00000000000000000000, ...
    0.13165249758739585347, ...
    0.065543462815238228565, ...
   -0.45765755436028576375, ...
   -7.0152525514345334694, ...
    0.86369115445061661395, ...
   -0.29581291553274554043 ];
  x_vec = [ ...
   0.083333333333333333333, ...
   0.26179938779914943654, ...
   0.50000000000000000000, ...
   0.52359877559829887308, ...
   0.78539816339744830962, ...
   1.0000000000000000000, ...
   1.0471975511965977462, ...
   1.3089969389957471827, ...
   1.5707963267948966192, ...
   1.4398966328953219010, ...
   1.5053464798451092601, ...
   2.0000000000000000000, ...
   3.0000000000000000000, ...
   4.0000000000000000000, ...
   5.0000000000000000000 ];

  if ( n_data < 0 )
    n_data = 0;
  end

  n_data = n_data + 1;

  if ( n_max < n_data )
    n_data = 0;
    x = 0.0;
    fx = 0.0;
  else
    x = x_vec(n_data);
    fx = fx_vec(n_data);
  end

  return
end
