КУБІЧНИЙ КОРІНЬ
function [ n_data, x, fx ] = cbrt_values ( n_data )
%*****************************************************************************80
%
%% CBRT_VALUES returns some values of the cube root function.
%
% Discussion:
%
% CBRT(X) = real number Y such that Y * Y * Y = X.
%
% In Mathematica, the function can be evaluated by:
%
% Sign[x] * ( Abs[x] )^(1/3)
%
% Licensing:
%
% This code is distributed under the GNU LGPL license.
%
% Modified:
%
% 22 June 2007
%
% 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.
%
% Parameters:
%
% Input/output, integer N_DATA. The user sets N_DATA to 0 before the
% first call. 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.
%
% Output, real X, the argument of the function.
%
% Output real FX, the value of the function.
%
n_max = 14;
fx_vec = [ ...
0.0000000000000000E+00, ...
-0.0020082988563383484484E+00, ...
0.44814047465571647087E+00, ...
-0.46415888336127788924E+00, ...
0.73680629972807732116E+00, ...
-1.0000000000000000000E+00, ...
1.2599210498948731648E+00, ...
-1.4422495703074083823E+00, ...
1.4645918875615232630E+00, ...
-2.6684016487219448673E+00, ...
3.0723168256858472933E+00, ...
-4.1408177494228532500E+00, ...
4.5947008922070398061E+00, ...
-497.93385921817447440E+00 ];
x_vec = [ ...
0.0000000000000000E+00, ...
-0.8100000073710001E-08, ...
0.9000000000000000E-01, ...
-0.1000000000000000E+00, ...
0.4000000000000000E+00, ...
-0.1000000000000000E+01, ...
0.2000000000000000E+01, ...
-0.3000000000000000E+01, ...
0.3141592653589793E+01, ...
-0.1900000000000000E+02, ...
0.2900000000000000E+02, ...
-0.7100000000000000E+02, ...
0.9700000000000000E+02, ...
-0.1234567890000000E+09 ];
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
