function [y1,T,y0] = prob9(t,y,jaco)
%
% [alpha,T,y0] = prob9
%
% or
%            f = prob9(t,y)
%
% or
%           f' = prob9(t,y,1)
%
% or
%            y = prob9(t)
%
% Problem 9  in:
%
%  L.Brugnano, G.Gurioli, F.Iavernaro, M.Vikerpuur. 
%  FDE-testset: comparing Matlab© codes for solving fractional
%  differential equations of Caputo type
%  Fractal Fract. 2025, 9(5), 312; https://doi.org/10.3390/fractalfract9050312
%
% 
alfa = 0.7;
A    = 1;
B    = 3;
if nargin==0    % problem data
    y1   = alfa;
    T    = 200;
    y0   = [1.2 2.8];
elseif nargin==1 
    if t==200
    % y(T) has been computed by [t,y]=fhbvm2('prob9',y0,T,1000,50,1000);
       y1 = [7.631553414699944e-01  3.337314189814776e+00];  % =>  h0=3e-10
    else
       y1 = [];
    end   
elseif nargin==2 % vector field
    if length(t)>1
       y1 = [A-(B+1)*y(:,1)+y(:,1).^2.*y(:,2) B*y(:,1)-y(:,1).^2.*y(:,2)];
    else
       y1 = [A-(B+1)*y(1)+y(1)^2*y(2); B*y(1)-y(1)^2*y(2)];
    end        
else             % Jacobian
    y1   = [-(B+1)+2*y(1)*y(2) y(1)^2; B-2*y(1)*y(2) -y(1)^2];
end
return


           