function [y1,T,y0] = prob2(t,y,jaco)
%
% [alpha,T,y0] = prob2
%
% or
%            f = prob2(t,y)
%
% or
%           f' = prob2(t,y,1)
%
% or
%            y = prob2(t)
%
% Problem 2 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 = 0.5;
if nargin==0    % problem data
    y1   = alfa;
    T    = 10;
    y0   = 10;
elseif nargin==1 % solution
    ybar = 1;
    y0   = 10;
    y1   = ml(-20*t.^alfa,alfa)*(y0-ybar)+ybar;
elseif nargin==2 % vector field
    y1   = 20-20*y;
else             % Jacobian
    y1   = -20;
end
return
