function [feature]  = HRV_PS_BLACKSWAN (R_i2, sampleRate)
%%
% INPUT:
% R_i2
% sampleRate
%
% OUTPUT:
% feature
%=======================================================================
% Authors' contact:
% Morteza Zabihi (morteza.zabihi@gmail.com) & Ali Bahrami Rad(abahramir@gmail.com)
% Black Swan Team (April 2017)
%=======================================================================
% This code is released under the GNU General Public License.
% You should have received a copy of the GNU General Public License along with this program.
% If not, see <http://www.gnu.org/licenses/>.

% By accessing the code through Physionet webpage and/or by installing, copying, or otherwise
% using this software, you agree to be bounded by the terms of GNU General Public License.
% If you do not agree, do not install copy or use the software.

% We make no representation about the suitability of this licensed deliverable for any purppose.
% It is provided "as is" without express or implied warranty of any kind.
% Any use of the licensed deliverables must include the above disclaimer.
% For more detailed information please refer to "readme" file.
%%
rng(0)

if length(R_i2)> 5

    RR = diff(R_i2')/sampleRate;
    %%
    [T, ~] = phasespace(RR, 2, 1);        
    %%
    ellipse_t = fit_ellipse( T(:,1), T(:,2));
    %%
    if ~isempty(ellipse_t.a)
             f10 = 0;
    else
            f10 = 1;
    end
else
     f10 = 0;
end

feature =  [f10];